British Journal of Haematology, 1977,36, 373.
Occurrence of Acute Leukaemia in Myeloproliferative Disorders DAVIDS . ROSENTHAL AND WILLIAM C. MOLONEY
Department of Medicine, Division of Hematology, Peter Bent Brighant Hospital, and Harvard Medical School, Boston, Massachusetts (Received 21 July 1976; acceptedfor publication 17January 1977) SUMMARY. In a series of 306 cases of myeloproliferative disorders followed over a period of 21 years, 18 cases of well-documented acute leukaemia were encountered. Leukaemias were either acute myeloblastic or myelomonocytic and occurred from 6 months to 20 years after the initial diagnosis. Onset was relatively abrupt and the course rapidly fatal with a median survival of 4 weeks. Due to the prolonged preleukaemic phase, it was possible to carry out a variety of clinical and laboratory observations. While no consistent features were noted, dysplastic haemopoiesis, a fall in leucocyte alkaline phosphatase activity, presence of Pelger-Huet anomaly and other abnormalities suggest a disturbance in granulocytic maturation. These findings suggest that, following an initial injury to a pleuripotentid haemopoietic stem cell, a prolonged ‘latent’ period occurs and, due to exposure to additional injurious agents or to a lack of cell regulating factors, acute leukaemia develops.
It is generally accepted that there is an increased incidence of leukaemia among patients with myeloproliferative disorders (MPD). While a great many studies have been published on clinical and pathological aspects of these diseases, the relationship between MPD and leukaemia remains obscure (Ward &Block, 1971;Lazlo, 1975). However, leukaemia occurring in patients with MPD affords a unique opportunity to study the haematological and other features of the pre and early leukaemic state. In this paper, observations are presented on 18 patients who were followed during the course of their MPD and developed leukaemia. Possible mechanisms of leukaemogenesis in these cases are discussed. METHODS In a series of 306 patients with MPD followed from I July 1954 to 3 0 June 1975, there were I 36 cases of polycythaemia Vera (PV), 162 w ith agnogenic myeloid metaplasia with myelofibrosis (AMM) and eight with essential thrombocythaemia (ET). Criteria for the diagnosis of PV and AMM were similar to those recently proposed by the Polycythaemia Vera Study Group (Laszlo, 1975 ; Berlin, 1975). History of exposure to benzene, ionizing radiation or other potentially toxic agents was investigated. Blood studies included a complete blood count, reticulocyte and platelet counts. Peripheral blood smears were carefully examined for the presence of red cell, granuCorrespondence:Dr David S. Rosenthd, 721 Huntington Avenue, Boston,Massachusetts 02115.U S A .
373
David S.Rosenthal and William C. M o b n e y
3 74
locyte and platelet abnormalities. Renal and liver h c t i o n tests were routinely obtained as well as serum uric acid, calcium, phosphorus and glucose levels. In some cases, serum folate, serum vitamin BIZ and Bi2-binding protein were determined along with serum iron and total iron binding capacity. In some cases where the diagnosis of PV was in question, total red cell and plasma volumes were measured by isotopic methods. Leucocyte alkaline phosphatase (LAP) activity was routinely determined and ofien repeated during the course of the disease. Serum and urine lysozyme levels were obtained in patients followed since 1967. In view of the problems of morphological identification of leukaemic cells, histochemical stains for myeloperoxidase activity (MPA) and specific granulocyte esterase were carried out when indicated (Moloney et al, 1960).Cytogenetic studies were carried out on marrow preparations and, in some cases, on b d y coats of peripheral blood cells. Bone marrow aspirations were performed routinely and the Wright-Giemsa (W/G) stained coverslips were reviewed by the authors. Bone marrow biopsies obtained &.om the posterior iliac crest were either fuced in formalin and stained with haematoxylin and eosin (H & E) or, in most instances, fixed in Zenker’s solution and stained with Giemsa. In a few cases, material was obtained by splenic aspiration and stained with W/G. When a decision regarding splenectomy or radiation to the spleen had to be made, patients were admitted for a more detailed evaluation which included red cell survival, ferrokmetics and bone marrow scintigraphy. Results of special radioisotopic studies on some of these cases have been reported (Button et al, 1974;McNeil et al, 1974).
RESULTS Total Series At the time of analysis, out of 306 patients, 200 were alive, 100 had died and six were lost to follow-up. Average age at the time of the diagnosis of the MPD was 63.8 years, with a range of 24-94 years. Male to female ratio was I : I (see Table I). Leukaemia developed in TABLE I. 306 cases of MPD: age, sex and other data Ave.
PV AMM ET
Total
F
M
Alive
Dead
136 162 8
81 63 6
S5 99
99 94
35
2
59.1
31-82
64
4
24-94
2
7
I
0
65.8 52.6
306
150
156
200
100
6
63.8
24-94
LTFU*
age (ur)
Range (yr)
31-81
Lost to follow-up.
18 patients (6%) ;eight in 136 with PV (6%) ;nine in 162with AMM (5.6%) and one in eight patients with ET. Among the leukaemic cases, the average age at onset of MPD was 59,with a range of 31-75 years; the male to female ratio was 13.5 (see Table 11). All cases of chronic granulocytic leukaemia were excluded from this evaluation.
Occurrence of Acute Leukaemia in Myeloproliferative Disorders
3 75
TABLE 11. Age and sex of 18 patients with MPD developing leukaemia At onset
./MPD
At onset of leukaemia
Sex
Range
Ave.
Range
M
55 62
31-65 43-75
65
42-82 44-76
5
3
66
8
2
59
31-75
6s
42-82
I3
5
Ave.
F
~~
PV AMM* Total
* Includes one case of essential thrombocythaemia. Leukaemia in PV Patients Of the eight cases of leukaemia developing in the PV group, five were males, three females. Average age at onset of PV was 55, with a range of 31-65 years. Duration of PV averaged 10 years with a range of 2.5-20. As noted in Table IIIA, most of the PV patients had usual diagnostic, clinical and laboratory features. All but one presented with an enlarged spleen and two had gastrointestinal bleeding at the onset. Blood studies prior to therapy were typical and elevated platelet counts were present in most cases. Markedly elevated leucocyte counts were noted in four cases but differentials were characteristic of PV. LAP was greatly elevated in six of seven cases. In one instance (Case j ) , late in the course of PV, the LAP score was 0. Cytogenetic studies were attempted in four cases; no metaphases were obtained on two occasions and, in Cases 2 and 4, marrow specimens were inadequate due to myelofibrosis. In four cases the marrow was hypercellular with abnormal megakaryocytes, but no myelofibrosis was noted. Case 3, with persistent marked eosinophilia, was of special interest since the marrow 4 years before the diagnosis of leukaemia showed dysplastic erythroid and myeloid elements. In addition to immature eosinophils, a large percentage of neutrophils showed striking Pelger-Huet abnormalities. Of the eight leukaemic patients, all but one had been treated with alkylating agents including busulphan, phenyl-alanine mustard or chlorambucil. In addition, three received radiation therapy to the spleen late in the course of PV, while two patients were treated with radioactive phosphorus ("P) in addition to alkylating agents. Case 8, a patient with a prolonged course of PV, had splenectomy 4 years prior to development of leukaemia. The onset of leukaemia was variable, but in most cases was associated with a progressively enlarging spleen and the appearance of blasts and myelomonocytic cells in the peripheral blood. In only two cases, Cases 5 and 8, did the absolute number of leukaemic cells in the peripheral blood not increase. However, in both cases, the marrow was replaced by sheets of blast forms. Systemic symptoms including fever, weight loss, night sweats and weakness occurred in four cases. In Case 4 the leukaemic onset was heralded by the appearance of a diffuse, ham-coloured nodular skin rash. Biopsy of the lesions revealed leukaemia cutis. Case 8 developed intractable gastrointestinal bleeding associated with thrombocytopenia which was the terminal event. No anti-leukaemic chemotherapy was attempted in four cases. Single agents were tried in two cases and combined chemotherapy CAT (cytosine arabinoside and 6-thioguanine) and COAP (cyclophosphamide, Oncovin, cytosine arabino-
0.38
0.25
038
IZI
8.0
9.1
6
7
8
0.28
s
0.17
5.9
8.3
4
0.29
7.1
3
0.26
7.9
2
BI&ding, prior SPLneaomy
VM
J.B.
8 w
t
*hbhg
phkbotomy.
phlebotomy
-WY
16yeur
3zmonths
Duration
Hb
17.8
20.5
(gldl)
Normal Normal
28.0 @.O
7.6
0.49 0.75 0.51 52.0
occ NRBC
9.0
0.57
0.60
Hypaplastic -Yd& Not done
25./
0.73
occ NRBC
Normal
&oPm
16.0
0.60
Bonemanow
ND+
D8mential Normal N o d
10.5 18.0
Platskt
0.65
WBC
x r d l l . xr@ll.
PCV
9.6
z0s.o
n . 0
41.0
55.0
63.0
26.0
20.0
20&0
43.0
105.0
41.0
3.0
8.0
Myclomonoblasts26%
MyclobIasts50%. OCCNRBC MPA positive Myelomonoblutr8j%
Blasa 10%
Blutrocc PClga-HW allr Myelomomocytcc 53%
BIYts36%
360
Notdone
345
0
57
Notdone
Mydofibrosirwith myclomonoblvtr Myelofibrctsbwith mycloblasts
b M b y mydoblasts Slight myclofibrosir with mycloblasa
MycMbrosu with 59% myclomonoblasts Zd$g&Y
.
4 week3
AMML
AMML
week
None
1 week,
I
Ara-C
AML I
None
weck
I
AML
AMML
AEL
AMML.
368
Notdone
Normalstudy
308
o
cyto&?ewricr unrucmsful
LAP
wak
12 months
None
6MP
6-MP.coAp 7 W d u
Splenic irradiation
TABLE IIIB. Clinical and laboratory data: patients with PV developing leukaemia. leukaemic stage
Splcnomcgdy
6-
Clinical
LD.
&/Sex
I
NO. Case
TABLE IIIA. Clinical and laboratory data: patient with PV developing leukaemia, pre-leukaemic stage
s
v
z
K’
z
z
3
0
k
’ 6 In
a
W
Occurrence ofAcute Leukaemia in Myeloproliferative Disorders
3 77 side and prednisone) were administered in two patients without benefit. In all eight cases bone marrow aspiration carried out at the onset of leukaemia revealed replacement by myeloblasts and/or myelomonocytic cells. In addition, biopsies showed persistent myelofibrosis in four cases. Autopsies were carried out in seven of eight cases and diffuse organ idiltration confirmed the diagnosis of acute leukaemia. Of unusual interest was the presence of greatly elevated serum and urine lysozyme in Case I, which terminated in death with renal failure (Skarin ct al, 1972). In Case 2 , CNS symptoms led to discovery of leukaemic cells in the spinal fluid and at autopsy, infiltration of the brain by leukaemic cells. The presence of eosinophilic myelocytes and promyelocytes diffusely infiltrating not only the marrow but also the heart, lungs, kidneys and other organs substantiated the diagnosis of acute eosinophilic leukaemia in Case 3. Another patient, Case 5, who developed severe pulmonary insufficiency late in the course of PV, showed at autopsy not only evidence of leukaemic infiltration but also pulmonary fibrosis consistent with busulphan toxicity.
Lerrkaemia in AMM Patients In the 10 patients with AMM, including the case of ET, the average age at diagnosis of leukaemia was 66 with a range of 4 - 7 6 ; the male to female incidence was 8 :z (see Table 11). Median duration of AMM was 3.7 years, with a range of 6 months to 9 years. Clinical frndings at the onset of MPD were variable (see Table IV). Eight of 10 patients presented with an enlarged spleen and, in Case 12, the diagnosis was made following emergency splenectomy for spontaneous rupture of that organ. In none of the cases were the haematocrit or haemoglobin elevated; in fact, two were mildly and two were severely anaemic when the diagnosis was first established. Leucocyte counts were variable; five were in the normal range, four moderately and one greatly elevated. Abnormalities in the peripheral blood included lymphopenia, ‘shift to the lefi’ with small numbers of immature granulocytes, nucleated red cells and characteristic changes in red cell morphology. Platelet counts also varied, ranging from 20x 10~11.to 1500x 10~11. Leucocyte alkaline phosphatase activity was determined in nine cases. It was absent in two, slightly to moderately elevated in four and greatly elevated in three cases. Cytogenetic analysis was attempted from bone marrow material in all 10 cases. No metaphases were obtained in three, no abnormalities were found in four, while aneuploidy with a deletion or addition of a C chromosome was noted in two patients. In Case 14, the initial chromosome study failed to reveal abnormalities but aneuploidywith the presence of the Philadelphia chromosome was documented on later studies. In all 10 cases bone marrow biopsies were carried out and marked myelofibrosis was present in six cases, myelofibrosis with hypercellularity and dysplastic megakaryocytes in three cases. In Case 9, the marrow biopsy showed a hyperplastic, panmyelocytic picture without myelofibrosis. Treatment in the MPD stage consisted of busulphan in two cases, phenylalanine mustard in two and chlorambucil following splenectomy in one case. Splenectomy without further treatment was employed in one case and two patients had splenectomy following radiation therapy to the spleen. Two patients received supportive therapy only. In the early stage of leukaemia, clinical features were ofien obscured by therapy and the nature of the underlying MPD. In Case 9, after an initial response to busulphan the patient
WBC
9.1
27.0
0.40
0.38
6.5 14.6
12.9
43M
71M
65M
53M
SSM
6gM
73F
L.W.
E.M.
S.G.
J-P.
R.R.
G.M.
L.M.
12
13
14
15
16
17
18 13.6
12.7
15.7
11.2
0.41
0.39
0.50
0.18
0.34
0.17
-
66M
F.T.
13.3
19.8
6.7
4-7
31.0
5.0
18.5
I1
0.38
12.4
53M
D.O.
75.0
x109lI.
I0
0.44
PCV
7SF
Massive splcnomegalY
Hb (g/dl.)
E.B.
Duration
9,
ThnnpY
I so0
345
137
700
236
m
234
60
40
450
Phtclets x10Sll.
N
W
Pdga-Huet
NRBC occ.
Normal
Normal
NRBC occ.
NRBC occ.
Normal
Pel--Huet ccllr
BLutr 6.5
NRBC occ.
NRBC occ.
LXfmential
TABUIVA. Clinical and laboratory data: patients with liMM developing ledca-.
1%
Marked
LZM
Mydofitnoait. ueu of
hyperdularity
Mydofibrmir
dulpity
0.71
231
t65
Notdone
Notdone
Notdone
Notdone
o Mydofibrosis Mydofiibrosis, Of h w -
Not*
o
Notdone Notdone
344
LAP
Myelofibrooir
Mycbfibmsis
Myelofibrosis
Bonenonow
pre-kukaemk stage
Normalstudy
Ndrtudy
Ndstudy
Utuucmrful
an cup lo id^
c group Ph Fintstudynormal.sccond study-Pb present with
Ancuploidp..
-
Uaruccesrful
Cytogenetb
00
W
15.0
135.0
43.0
35.0
76.0
0.4
0.21
0.33
0.17
0.30
0.30
0.19
0.32
0.31
8.2
7.I
10.4
5.6
ND
9.I
ND
10.1
10.7
I1
I2
13
14
IS
16
I7
I8
60.0
Mydoblasts 38%
Not done
Not done
Rcplaad by mydoblasts
Mydofibrosis,
with leukwnu
Replaad by mydoblasts
Dauno None
Cydo Va
Prcdnisone
Va,
None
6MP Va VAMP
Mydoblasts 4%
Not done
ND
6.0
100.0
55.0
102.0
180.0
320.0
Va
6-MP.
381.0
Myelomonocytes
COAP
6-MP. V a
Therapy of
leukncmia
6-MP
o
Mydofibrosis
Shatsof myclomonocytes
Bow mamow
Myelomoncxytu 62% Mydoblasts 60%
&5 Positive
Mydomonocytes
Edlso:our.NRBc
46
6
LAP
None
30.0
15.0
MYdommmtes MPA negative MydoblastJ5 1 7 Pelgcr-Huet
96%
DifferentiaJ
Mydoblasts 83%
14S.0
I 4I
$0.0
10
169.0
0.40
14.5
9
W B C Platelets x109/1. x1@/1.
PCV
(gldl)
No.
Hb
a=-
b
AML AML
AML
AML
Diffuse organ infiltration; persistcllt EMH Diffrut organ in6ltration Diffuse organ infiltration
3 weeks
3f months . W &
IWCCk
Not done
G;.
c
%i
s.
G
3.
%
pcrsirtcnt EMH
s-
5 montbs
2f mmtbs
AML
f;'
s
FF
ia"
% b 2
3 2
Not done
AML Diffuse organ infiltration
AMML
Diffrrv organ infiltration,
witb mydoblasts
D i f f i organ infiltration with mydomonocyta
AML
AMML
DiIiii organ in6ltxation with mydomonowta
Not done
Final pathologic diagnosis
Post-mmm, findings
T
s
0
AMML
I month
3 months
3 w-
2 w&
leukaemia
Duration of
TABLE IVB. Clinical and laboratory data: patients with A M M developing leukaemia, leukaemic stage
3 80
David S . Rosenthal and William C. Moloney
developed fever, a rapidly enlarging spleen, liver and lymphadenopathy. Serum and urinary lysozyme became elevated along with a rise in leucocytes to 169 x 10~11.with 90% myelomonocytes. The patient developed renal failure, hypokalaemia, septicaemia and died after a rapid downhill course. Another patient, Case 11, following a prolonged course of myelofibrosis with pancytopenia, underwent splenectomy and, within 6 weeks, developed obvious leukacmic transformation with a leucocyte count of 162x 10~11. consisting of over 60% myelomonocytes. This patient also developed a rise in serum and urinary lysozyme. He responded partially to dmercaptopurine, but quickly relapsed and died with gastrointestinal bleeding and septicaemia. Case 14 had several unusual features; the 6 year course was characterized by myelofibrosis, marked splenomegaly, ascites and a peripheral blood picture consistent with the diagnosis of AMM. Progressive splenic enlargement required radiation therapy to the spleen and, finally, splenectomy was carried out. The initial chromosome study, 24 years prior to the onset of leukaemia, produced poor metaphases but no Philadelphia chromosome was noted. Shortly before splenectomy and 6 weeks before the diagnosis of leukaemia, chromosome studies showed aneuploid metaphases with the presence of a Philadelphia chromosome. Following splenectomy, the patient symptomatically improved. However, the leucocytes and platelets rose and, 6 weeks after splenectomy, the leucocyte count was 180 x 10~11.with 60% myeloblasts. Treatment with dmercaptopurine, vincristine, prednisone and, finally, VAMP (vincristine,amethopterin, dmercaptopurine and prednisone) was ineffective and the patient died without achieving a remission. Cases 14-18 had rather sinlilar courses with the onset of leukaemia characterized by rapidly increasing leucocyte counts and a large percentage of myeloblasts. Bone marrow biopsy showed myelofibrosis with leukaemic infiltration in three cases and sheets of myeloblasts without fibrosis in the other two patients. Four of these five cases at autopsy showed diffuse organ infiltration. In addition, extramedullary haemopoiesis was present in the liver and spleen in Cases 13 and IS. The youngest patient, Case 12,had a relatively short and unusual course. Diagnosis of AMM was established following splenectomy for spontaneous rupture of the spleen. At that time, the marrow was severely myelofibrotic. He required no therapy but, 17months later, was readmitted with the diagnosis of ruptured appendix. At the time of laparotoniy, generalized lymphadenopathywas noted without any evidenceof peritonitis. Postoperatively, the leucocyte count rose to 180x 10~11.with 83% myeloblasts. The patient died soon afterwards and autopsy showed diffuse leukaemic infiltration of organs and replacement of the marrow with myeloblasts. Case 10 represented the most bizarre course in this series. He initially presented with a very large spleen, normal haematocrit and slightly elevated leucocyte count with mild thrombocytopenia. Peripheral blood smears showed characteristic myeloid and red cell changes, including nucleated red cells. Bone marrow biopsy revealed myelofibrosis with greatly increased and severely dysplastic megakaryocytes. Chromosome study disclosed aneuploidy with loss of a C chromosome but no Philadelphia chromosome. A splenic aspiration showed a cellular preparation with erythroid, myeloid and megakaryocytic elements. The patient developed diffuse, painful swelling of the lower extremities associated with subcutaneous nodules and generalized lymphadenopathy. Biopsies of the skin, subcutaneous nodules and several lymph nodes revealed extramedullary haemopoiesis and infiltration with bizarre megakaryoblasts and megakaryocytes. Treatment with prednisone and local irradiation resulted in regression of the subcutaneous swelling and enlarged
Occurrence of Acute Leukaemia in Myeloprolijkative Disorders
381
lymph nodes. However, myeloblasts appeared in the peripheral blood along with red cell abnormalities, including Cabot ring bodies. A course of COAP therapy was attempted but the patient failed to respond and died within 3 weeks. A bone marrow biopsy carried out following COAP therapy showed diffuse myelofibrosis. Unfortunately, in this case, an autopsy was not obtained. DISCUSSION The increased incidence of leukaemia among patients with MPD seems well established. However, in reported series of cases, the incidence varies from 5% to 25% (Dameshek, 1951; Wasserman, 1954; Lawrence et d, 1969; Silverstein & Linman, 1969; Rosenthal & Moloney, 1969; Landaw, 1976). Chief reasons for this variability are the difficulties of establishing an unequivocal diagnosis of leukaemia and the problem of excluding atypical forms of chronic granulocytic leukaemia (CGL) entering blast cell crisis. In this study, strict criteria were used to establish the diagnosis of acute leukaemia and several cases were excluded from this report due to incomplete data. It is strongly suspected that the incidence of leukaemia is higher than the data suggests. As noted in Tables I11 and IV, a variety of methods were employed in the treatment of MPD and 12 of 18 patients received alkylating agents during the course of their disease. Only two patients were treated with "P, five underwent splenectomy, two had radiation therapy to the spleen and four cases received no chemotherapy or radiation. MPD patients are apparently predisposed to develop acute leukaemia and it is possible that alkylating agents also play a leukaemogenic role. However, the nature of the relationship between chemotherapeutic agents and the occurrence of leukaemia is not known. Some of the general features of acute leukaemia developing in patients with MPD are of interest. All 18 leukaemias were acute myeloblastic or myelomonocytic. Both in PVand AMM groups, leukaemia occurred in older adults and especially among males. The pre-leukaemic state was considerably longer in PV than AMM but the age at onset of leukaemia was similar in both groups. The long course of the MPD permitted repeated haematological and other studies. While no consistent findings were noted, a number of abnormalities seem to be important in separating out the pre-leukaemic cases. In several instances markedly dysplastic haemopoiesis was present months to years prior to the diagnosis of acute leukaemia. The development of the Pelger-Huet anomaly, a profound fall in previously elevated LAP scores, loss of MPA in segmented neutrophils, a marked rise in serum and urinary lysozyme at the onset of leukaemic phase, were all of special interest. These findings suggest a progressive disturbance in regulation of granulocytic maturation, possibly attributable to some form of somatic mutation. In this regard, three patients were noted to have aneuploidy prior to the diagnosis of leukaemia. In two cases, the abnormality involved the C chromosome. In no case of leukaemia was a complete remission obtained and the survival time was extremely short. Median survival was 3 weeks, with a range of 1-48 weeks; 12 of 18 cases died within 4 weeks. Poor response to chemotherapy and short survival are frequently observed in patients over 60 with acute myeloblastic leukaemia. In a recent analysis of 205 adult cases of AML followed over a 6 year period, we have noted that 98 of 205 patients were over 60 and, of
3 82
David S . Rosenthal and William C. Moloney
these, 50 had some preceding haematological disorder (Moloney & Rosenthal, unpublished data). These included 29 with refractory dysplastic anaemia, four with PV, five with aplastic anaemia and three with AMM. Patients with refractory, dysplastic anaemia shared many features noted in leukaemic MPD cases; they were older adults, predominantly males, had long pre-leukaemic states, responded poorly to chemotherapy and survival time was short. A consistent feature of these cases were the dysplastic changes found in the myeloid, erythroid and megakaryocytic precursors in the pre-leukaemic bone marrow. While the above observations do not explain the unfavourable course of AML in all older patients, interesting questions arise as to the nature of leukaemogenesis in this age group. It seems reasonable to postulate that, following an initial injury to a pleuripotential stem cell by viral, chemical, radiation, metabolic or immunological agents, the altered stem cell undergoes a prolonged latent period. During this time, due to additional exposure or possibly because of deficiencies of host maturation factors a variety of haematological disorders emerge. These include aplastic, metaplastic, hyperplastic, dysplastic and, in some instances, neoplastic disorders. The development of myeloblastic, myelomonocyticand erythromyelocytic leukaemias may be considered to be late events, possibly attributable to cell membrane changes, environmental factors or both. If this concept of leukaemogenesis is valid, it could explain the unfavourable course and poor response to chemotherapy in some older patients with AML. While aggressive chemotherapy might destroy leukaemic blast cells, no normal haematopoietic precursors would be available to repopulate the bone marrow. ACKNOWLEDGMENTS
Supported in part by National Institutes of Health, Division of Research Resources, GCRC Branch, Grant RR 00 888 and also the Nehemias G r i n Foundation. REFERENCES BERLIN, N.I. (1975)Diagnosis and classification of the polycythemias. Seminars in Hematology, Ia, 339. BUITON,L.N., ROSENTHAL, D.S., NATHAN,D.G. & MOLONBY, W.C. (1974)Computer evaluation of fmokinetics and p C r red cell survival in 37 patients with myeloid metaplasia. XIIth Intanational Society of Hematology, Jerusalem, Israel (Abstracts, p 163). DA~SHEK,W. (1951)Some speculations on the myeloprolifaativesyndromes. Blood, 6,372. LANDAW,S.A. (1976)Acute leukemia in polycythemia Vera. Seminars in Hematology, 13, 33. LAWRENCB, J.H., Wm-, H.S. & DONALD, W.G. (1969)Leukemia in polycythemia ven: relationship to splenic myeloid metaplasia and therapeutic radiation dose. Annals of Internal Medicine, 70, 763. LASZLO, J.(1975)Myeloproliferative disorders (MDP): myelofibrosis, myelosderosis, extramedullary hcmatopoiesis, undifferentiated MPD, and hemorrhagic thrombocythemia. Seminars in Hematology, 12, 409. McNm, B.J.,HOLMAN,B.L., BUITON,L.N. & ROSENTHAL, D.S. (1974)The use of indium chloride
scintigraphy in patients with myelofibrosis. Journal of Nuclear Medicine, 15, 647.
MOLONEY, W.C., MCP~IB~SON, K. & FLIBGBLMAN, L. (1960)Estuase activity in leukocytes demonstrated by the use of naphthol AS-D chloracetate substrate. Journal ofHistology and Cytochemistry, 8, 200. ROSBNTHAL, D.S. & MOLONEY, W.C. (1969)Myeloid metaplasia: a study of98 cases. Postgraduate Medicine, 46,136. S~vmts~apr, M.D. & L m w , J.W. (1969)Causes of death in agnogenic myeloid metaplasia. Mayo Clinic Proceedings, 4, 36. SKARIN.A.T., ~ Z U O Y. , & MOLONBY, W.C.(1972) Muramidase in myeloprolifaative disorders terd a t i n g in acute leukemia. Cancer, 19, 1336. W m .H.P. & BLOCK, M.H. (1971)The natural history of agnogenic myeloid metaplasia (AMM) and a critical evaluation of its relationship with the myeloproliferative syndrome. Medicine, 50, 3 57. WASSHBMAN, L.R (1954) Polycythemia Vera-its course and treatment: relation to myeloid metaplasia and leukemia. Bulletin of the New York Academy ofMedicine, 30, 343.
Occurrence of Acute Leukaemia in Myeloproliferative Disorders DAVIDS . ROSENTHAL AND WILLIAM C. MOLONEY
Department of Medicine, Division of Hematology, Peter Bent Brighant Hospital, and Harvard Medical School, Boston, Massachusetts (Received 21 July 1976; acceptedfor publication 17January 1977) SUMMARY. In a series of 306 cases of myeloproliferative disorders followed over a period of 21 years, 18 cases of well-documented acute leukaemia were encountered. Leukaemias were either acute myeloblastic or myelomonocytic and occurred from 6 months to 20 years after the initial diagnosis. Onset was relatively abrupt and the course rapidly fatal with a median survival of 4 weeks. Due to the prolonged preleukaemic phase, it was possible to carry out a variety of clinical and laboratory observations. While no consistent features were noted, dysplastic haemopoiesis, a fall in leucocyte alkaline phosphatase activity, presence of Pelger-Huet anomaly and other abnormalities suggest a disturbance in granulocytic maturation. These findings suggest that, following an initial injury to a pleuripotentid haemopoietic stem cell, a prolonged ‘latent’ period occurs and, due to exposure to additional injurious agents or to a lack of cell regulating factors, acute leukaemia develops.
It is generally accepted that there is an increased incidence of leukaemia among patients with myeloproliferative disorders (MPD). While a great many studies have been published on clinical and pathological aspects of these diseases, the relationship between MPD and leukaemia remains obscure (Ward &Block, 1971;Lazlo, 1975). However, leukaemia occurring in patients with MPD affords a unique opportunity to study the haematological and other features of the pre and early leukaemic state. In this paper, observations are presented on 18 patients who were followed during the course of their MPD and developed leukaemia. Possible mechanisms of leukaemogenesis in these cases are discussed. METHODS In a series of 306 patients with MPD followed from I July 1954 to 3 0 June 1975, there were I 36 cases of polycythaemia Vera (PV), 162 w ith agnogenic myeloid metaplasia with myelofibrosis (AMM) and eight with essential thrombocythaemia (ET). Criteria for the diagnosis of PV and AMM were similar to those recently proposed by the Polycythaemia Vera Study Group (Laszlo, 1975 ; Berlin, 1975). History of exposure to benzene, ionizing radiation or other potentially toxic agents was investigated. Blood studies included a complete blood count, reticulocyte and platelet counts. Peripheral blood smears were carefully examined for the presence of red cell, granuCorrespondence:Dr David S. Rosenthd, 721 Huntington Avenue, Boston,Massachusetts 02115.U S A .
373
David S.Rosenthal and William C. M o b n e y
3 74
locyte and platelet abnormalities. Renal and liver h c t i o n tests were routinely obtained as well as serum uric acid, calcium, phosphorus and glucose levels. In some cases, serum folate, serum vitamin BIZ and Bi2-binding protein were determined along with serum iron and total iron binding capacity. In some cases where the diagnosis of PV was in question, total red cell and plasma volumes were measured by isotopic methods. Leucocyte alkaline phosphatase (LAP) activity was routinely determined and ofien repeated during the course of the disease. Serum and urine lysozyme levels were obtained in patients followed since 1967. In view of the problems of morphological identification of leukaemic cells, histochemical stains for myeloperoxidase activity (MPA) and specific granulocyte esterase were carried out when indicated (Moloney et al, 1960).Cytogenetic studies were carried out on marrow preparations and, in some cases, on b d y coats of peripheral blood cells. Bone marrow aspirations were performed routinely and the Wright-Giemsa (W/G) stained coverslips were reviewed by the authors. Bone marrow biopsies obtained &.om the posterior iliac crest were either fuced in formalin and stained with haematoxylin and eosin (H & E) or, in most instances, fixed in Zenker’s solution and stained with Giemsa. In a few cases, material was obtained by splenic aspiration and stained with W/G. When a decision regarding splenectomy or radiation to the spleen had to be made, patients were admitted for a more detailed evaluation which included red cell survival, ferrokmetics and bone marrow scintigraphy. Results of special radioisotopic studies on some of these cases have been reported (Button et al, 1974;McNeil et al, 1974).
RESULTS Total Series At the time of analysis, out of 306 patients, 200 were alive, 100 had died and six were lost to follow-up. Average age at the time of the diagnosis of the MPD was 63.8 years, with a range of 24-94 years. Male to female ratio was I : I (see Table I). Leukaemia developed in TABLE I. 306 cases of MPD: age, sex and other data Ave.
PV AMM ET
Total
F
M
Alive
Dead
136 162 8
81 63 6
S5 99
99 94
35
2
59.1
31-82
64
4
24-94
2
7
I
0
65.8 52.6
306
150
156
200
100
6
63.8
24-94
LTFU*
age (ur)
Range (yr)
31-81
Lost to follow-up.
18 patients (6%) ;eight in 136 with PV (6%) ;nine in 162with AMM (5.6%) and one in eight patients with ET. Among the leukaemic cases, the average age at onset of MPD was 59,with a range of 31-75 years; the male to female ratio was 13.5 (see Table 11). All cases of chronic granulocytic leukaemia were excluded from this evaluation.
Occurrence of Acute Leukaemia in Myeloproliferative Disorders
3 75
TABLE 11. Age and sex of 18 patients with MPD developing leukaemia At onset
./MPD
At onset of leukaemia
Sex
Range
Ave.
Range
M
55 62
31-65 43-75
65
42-82 44-76
5
3
66
8
2
59
31-75
6s
42-82
I3
5
Ave.
F
~~
PV AMM* Total
* Includes one case of essential thrombocythaemia. Leukaemia in PV Patients Of the eight cases of leukaemia developing in the PV group, five were males, three females. Average age at onset of PV was 55, with a range of 31-65 years. Duration of PV averaged 10 years with a range of 2.5-20. As noted in Table IIIA, most of the PV patients had usual diagnostic, clinical and laboratory features. All but one presented with an enlarged spleen and two had gastrointestinal bleeding at the onset. Blood studies prior to therapy were typical and elevated platelet counts were present in most cases. Markedly elevated leucocyte counts were noted in four cases but differentials were characteristic of PV. LAP was greatly elevated in six of seven cases. In one instance (Case j ) , late in the course of PV, the LAP score was 0. Cytogenetic studies were attempted in four cases; no metaphases were obtained on two occasions and, in Cases 2 and 4, marrow specimens were inadequate due to myelofibrosis. In four cases the marrow was hypercellular with abnormal megakaryocytes, but no myelofibrosis was noted. Case 3, with persistent marked eosinophilia, was of special interest since the marrow 4 years before the diagnosis of leukaemia showed dysplastic erythroid and myeloid elements. In addition to immature eosinophils, a large percentage of neutrophils showed striking Pelger-Huet abnormalities. Of the eight leukaemic patients, all but one had been treated with alkylating agents including busulphan, phenyl-alanine mustard or chlorambucil. In addition, three received radiation therapy to the spleen late in the course of PV, while two patients were treated with radioactive phosphorus ("P) in addition to alkylating agents. Case 8, a patient with a prolonged course of PV, had splenectomy 4 years prior to development of leukaemia. The onset of leukaemia was variable, but in most cases was associated with a progressively enlarging spleen and the appearance of blasts and myelomonocytic cells in the peripheral blood. In only two cases, Cases 5 and 8, did the absolute number of leukaemic cells in the peripheral blood not increase. However, in both cases, the marrow was replaced by sheets of blast forms. Systemic symptoms including fever, weight loss, night sweats and weakness occurred in four cases. In Case 4 the leukaemic onset was heralded by the appearance of a diffuse, ham-coloured nodular skin rash. Biopsy of the lesions revealed leukaemia cutis. Case 8 developed intractable gastrointestinal bleeding associated with thrombocytopenia which was the terminal event. No anti-leukaemic chemotherapy was attempted in four cases. Single agents were tried in two cases and combined chemotherapy CAT (cytosine arabinoside and 6-thioguanine) and COAP (cyclophosphamide, Oncovin, cytosine arabino-
0.38
0.25
038
IZI
8.0
9.1
6
7
8
0.28
s
0.17
5.9
8.3
4
0.29
7.1
3
0.26
7.9
2
BI&ding, prior SPLneaomy
VM
J.B.
8 w
t
*hbhg
phkbotomy.
phlebotomy
-WY
16yeur
3zmonths
Duration
Hb
17.8
20.5
(gldl)
Normal Normal
28.0 @.O
7.6
0.49 0.75 0.51 52.0
occ NRBC
9.0
0.57
0.60
Hypaplastic -Yd& Not done
25./
0.73
occ NRBC
Normal
&oPm
16.0
0.60
Bonemanow
ND+
D8mential Normal N o d
10.5 18.0
Platskt
0.65
WBC
x r d l l . xr@ll.
PCV
9.6
z0s.o
n . 0
41.0
55.0
63.0
26.0
20.0
20&0
43.0
105.0
41.0
3.0
8.0
Myclomonoblasts26%
MyclobIasts50%. OCCNRBC MPA positive Myelomonoblutr8j%
Blasa 10%
Blutrocc PClga-HW allr Myelomomocytcc 53%
BIYts36%
360
Notdone
345
0
57
Notdone
Mydofibrosirwith myclomonoblvtr Myelofibrctsbwith mycloblasts
b M b y mydoblasts Slight myclofibrosir with mycloblasa
MycMbrosu with 59% myclomonoblasts Zd$g&Y
.
4 week3
AMML
AMML
week
None
1 week,
I
Ara-C
AML I
None
weck
I
AML
AMML
AEL
AMML.
368
Notdone
Normalstudy
308
o
cyto&?ewricr unrucmsful
LAP
wak
12 months
None
6MP
6-MP.coAp 7 W d u
Splenic irradiation
TABLE IIIB. Clinical and laboratory data: patients with PV developing leukaemia. leukaemic stage
Splcnomcgdy
6-
Clinical
LD.
&/Sex
I
NO. Case
TABLE IIIA. Clinical and laboratory data: patient with PV developing leukaemia, pre-leukaemic stage
s
v
z
K’
z
z
3
0
k
’ 6 In
a
W
Occurrence ofAcute Leukaemia in Myeloproliferative Disorders
3 77 side and prednisone) were administered in two patients without benefit. In all eight cases bone marrow aspiration carried out at the onset of leukaemia revealed replacement by myeloblasts and/or myelomonocytic cells. In addition, biopsies showed persistent myelofibrosis in four cases. Autopsies were carried out in seven of eight cases and diffuse organ idiltration confirmed the diagnosis of acute leukaemia. Of unusual interest was the presence of greatly elevated serum and urine lysozyme in Case I, which terminated in death with renal failure (Skarin ct al, 1972). In Case 2 , CNS symptoms led to discovery of leukaemic cells in the spinal fluid and at autopsy, infiltration of the brain by leukaemic cells. The presence of eosinophilic myelocytes and promyelocytes diffusely infiltrating not only the marrow but also the heart, lungs, kidneys and other organs substantiated the diagnosis of acute eosinophilic leukaemia in Case 3. Another patient, Case 5, who developed severe pulmonary insufficiency late in the course of PV, showed at autopsy not only evidence of leukaemic infiltration but also pulmonary fibrosis consistent with busulphan toxicity.
Lerrkaemia in AMM Patients In the 10 patients with AMM, including the case of ET, the average age at diagnosis of leukaemia was 66 with a range of 4 - 7 6 ; the male to female incidence was 8 :z (see Table 11). Median duration of AMM was 3.7 years, with a range of 6 months to 9 years. Clinical frndings at the onset of MPD were variable (see Table IV). Eight of 10 patients presented with an enlarged spleen and, in Case 12, the diagnosis was made following emergency splenectomy for spontaneous rupture of that organ. In none of the cases were the haematocrit or haemoglobin elevated; in fact, two were mildly and two were severely anaemic when the diagnosis was first established. Leucocyte counts were variable; five were in the normal range, four moderately and one greatly elevated. Abnormalities in the peripheral blood included lymphopenia, ‘shift to the lefi’ with small numbers of immature granulocytes, nucleated red cells and characteristic changes in red cell morphology. Platelet counts also varied, ranging from 20x 10~11.to 1500x 10~11. Leucocyte alkaline phosphatase activity was determined in nine cases. It was absent in two, slightly to moderately elevated in four and greatly elevated in three cases. Cytogenetic analysis was attempted from bone marrow material in all 10 cases. No metaphases were obtained in three, no abnormalities were found in four, while aneuploidy with a deletion or addition of a C chromosome was noted in two patients. In Case 14, the initial chromosome study failed to reveal abnormalities but aneuploidywith the presence of the Philadelphia chromosome was documented on later studies. In all 10 cases bone marrow biopsies were carried out and marked myelofibrosis was present in six cases, myelofibrosis with hypercellularity and dysplastic megakaryocytes in three cases. In Case 9, the marrow biopsy showed a hyperplastic, panmyelocytic picture without myelofibrosis. Treatment in the MPD stage consisted of busulphan in two cases, phenylalanine mustard in two and chlorambucil following splenectomy in one case. Splenectomy without further treatment was employed in one case and two patients had splenectomy following radiation therapy to the spleen. Two patients received supportive therapy only. In the early stage of leukaemia, clinical features were ofien obscured by therapy and the nature of the underlying MPD. In Case 9, after an initial response to busulphan the patient
WBC
9.1
27.0
0.40
0.38
6.5 14.6
12.9
43M
71M
65M
53M
SSM
6gM
73F
L.W.
E.M.
S.G.
J-P.
R.R.
G.M.
L.M.
12
13
14
15
16
17
18 13.6
12.7
15.7
11.2
0.41
0.39
0.50
0.18
0.34
0.17
-
66M
F.T.
13.3
19.8
6.7
4-7
31.0
5.0
18.5
I1
0.38
12.4
53M
D.O.
75.0
x109lI.
I0
0.44
PCV
7SF
Massive splcnomegalY
Hb (g/dl.)
E.B.
Duration
9,
ThnnpY
I so0
345
137
700
236
m
234
60
40
450
Phtclets x10Sll.
N
W
Pdga-Huet
NRBC occ.
Normal
Normal
NRBC occ.
NRBC occ.
Normal
Pel--Huet ccllr
BLutr 6.5
NRBC occ.
NRBC occ.
LXfmential
TABUIVA. Clinical and laboratory data: patients with liMM developing ledca-.
1%
Marked
LZM
Mydofitnoait. ueu of
hyperdularity
Mydofibrmir
dulpity
0.71
231
t65
Notdone
Notdone
Notdone
Notdone
o Mydofibrosis Mydofiibrosis, Of h w -
Not*
o
Notdone Notdone
344
LAP
Myelofibrooir
Mycbfibmsis
Myelofibrosis
Bonenonow
pre-kukaemk stage
Normalstudy
Ndrtudy
Ndstudy
Utuucmrful
an cup lo id^
c group Ph Fintstudynormal.sccond study-Pb present with
Ancuploidp..
-
Uaruccesrful
Cytogenetb
00
W
15.0
135.0
43.0
35.0
76.0
0.4
0.21
0.33
0.17
0.30
0.30
0.19
0.32
0.31
8.2
7.I
10.4
5.6
ND
9.I
ND
10.1
10.7
I1
I2
13
14
IS
16
I7
I8
60.0
Mydoblasts 38%
Not done
Not done
Rcplaad by mydoblasts
Mydofibrosis,
with leukwnu
Replaad by mydoblasts
Dauno None
Cydo Va
Prcdnisone
Va,
None
6MP Va VAMP
Mydoblasts 4%
Not done
ND
6.0
100.0
55.0
102.0
180.0
320.0
Va
6-MP.
381.0
Myelomonocytes
COAP
6-MP. V a
Therapy of
leukncmia
6-MP
o
Mydofibrosis
Shatsof myclomonocytes
Bow mamow
Myelomoncxytu 62% Mydoblasts 60%
&5 Positive
Mydomonocytes
Edlso:our.NRBc
46
6
LAP
None
30.0
15.0
MYdommmtes MPA negative MydoblastJ5 1 7 Pelgcr-Huet
96%
DifferentiaJ
Mydoblasts 83%
14S.0
I 4I
$0.0
10
169.0
0.40
14.5
9
W B C Platelets x109/1. x1@/1.
PCV
(gldl)
No.
Hb
a=-
b
AML AML
AML
AML
Diffuse organ infiltration; persistcllt EMH Diffrut organ in6ltration Diffuse organ infiltration
3 weeks
3f months . W &
IWCCk
Not done
G;.
c
%i
s.
G
3.
%
pcrsirtcnt EMH
s-
5 montbs
2f mmtbs
AML
f;'
s
FF
ia"
% b 2
3 2
Not done
AML Diffuse organ infiltration
AMML
Diffrrv organ infiltration,
witb mydoblasts
D i f f i organ infiltration with mydomonocyta
AML
AMML
DiIiii organ in6ltxation with mydomonowta
Not done
Final pathologic diagnosis
Post-mmm, findings
T
s
0
AMML
I month
3 months
3 w-
2 w&
leukaemia
Duration of
TABLE IVB. Clinical and laboratory data: patients with A M M developing leukaemia, leukaemic stage
3 80
David S . Rosenthal and William C. Moloney
developed fever, a rapidly enlarging spleen, liver and lymphadenopathy. Serum and urinary lysozyme became elevated along with a rise in leucocytes to 169 x 10~11.with 90% myelomonocytes. The patient developed renal failure, hypokalaemia, septicaemia and died after a rapid downhill course. Another patient, Case 11, following a prolonged course of myelofibrosis with pancytopenia, underwent splenectomy and, within 6 weeks, developed obvious leukacmic transformation with a leucocyte count of 162x 10~11. consisting of over 60% myelomonocytes. This patient also developed a rise in serum and urinary lysozyme. He responded partially to dmercaptopurine, but quickly relapsed and died with gastrointestinal bleeding and septicaemia. Case 14 had several unusual features; the 6 year course was characterized by myelofibrosis, marked splenomegaly, ascites and a peripheral blood picture consistent with the diagnosis of AMM. Progressive splenic enlargement required radiation therapy to the spleen and, finally, splenectomy was carried out. The initial chromosome study, 24 years prior to the onset of leukaemia, produced poor metaphases but no Philadelphia chromosome was noted. Shortly before splenectomy and 6 weeks before the diagnosis of leukaemia, chromosome studies showed aneuploid metaphases with the presence of a Philadelphia chromosome. Following splenectomy, the patient symptomatically improved. However, the leucocytes and platelets rose and, 6 weeks after splenectomy, the leucocyte count was 180 x 10~11.with 60% myeloblasts. Treatment with dmercaptopurine, vincristine, prednisone and, finally, VAMP (vincristine,amethopterin, dmercaptopurine and prednisone) was ineffective and the patient died without achieving a remission. Cases 14-18 had rather sinlilar courses with the onset of leukaemia characterized by rapidly increasing leucocyte counts and a large percentage of myeloblasts. Bone marrow biopsy showed myelofibrosis with leukaemic infiltration in three cases and sheets of myeloblasts without fibrosis in the other two patients. Four of these five cases at autopsy showed diffuse organ infiltration. In addition, extramedullary haemopoiesis was present in the liver and spleen in Cases 13 and IS. The youngest patient, Case 12,had a relatively short and unusual course. Diagnosis of AMM was established following splenectomy for spontaneous rupture of the spleen. At that time, the marrow was severely myelofibrotic. He required no therapy but, 17months later, was readmitted with the diagnosis of ruptured appendix. At the time of laparotoniy, generalized lymphadenopathywas noted without any evidenceof peritonitis. Postoperatively, the leucocyte count rose to 180x 10~11.with 83% myeloblasts. The patient died soon afterwards and autopsy showed diffuse leukaemic infiltration of organs and replacement of the marrow with myeloblasts. Case 10 represented the most bizarre course in this series. He initially presented with a very large spleen, normal haematocrit and slightly elevated leucocyte count with mild thrombocytopenia. Peripheral blood smears showed characteristic myeloid and red cell changes, including nucleated red cells. Bone marrow biopsy revealed myelofibrosis with greatly increased and severely dysplastic megakaryocytes. Chromosome study disclosed aneuploidy with loss of a C chromosome but no Philadelphia chromosome. A splenic aspiration showed a cellular preparation with erythroid, myeloid and megakaryocytic elements. The patient developed diffuse, painful swelling of the lower extremities associated with subcutaneous nodules and generalized lymphadenopathy. Biopsies of the skin, subcutaneous nodules and several lymph nodes revealed extramedullary haemopoiesis and infiltration with bizarre megakaryoblasts and megakaryocytes. Treatment with prednisone and local irradiation resulted in regression of the subcutaneous swelling and enlarged
Occurrence of Acute Leukaemia in Myeloprolijkative Disorders
381
lymph nodes. However, myeloblasts appeared in the peripheral blood along with red cell abnormalities, including Cabot ring bodies. A course of COAP therapy was attempted but the patient failed to respond and died within 3 weeks. A bone marrow biopsy carried out following COAP therapy showed diffuse myelofibrosis. Unfortunately, in this case, an autopsy was not obtained. DISCUSSION The increased incidence of leukaemia among patients with MPD seems well established. However, in reported series of cases, the incidence varies from 5% to 25% (Dameshek, 1951; Wasserman, 1954; Lawrence et d, 1969; Silverstein & Linman, 1969; Rosenthal & Moloney, 1969; Landaw, 1976). Chief reasons for this variability are the difficulties of establishing an unequivocal diagnosis of leukaemia and the problem of excluding atypical forms of chronic granulocytic leukaemia (CGL) entering blast cell crisis. In this study, strict criteria were used to establish the diagnosis of acute leukaemia and several cases were excluded from this report due to incomplete data. It is strongly suspected that the incidence of leukaemia is higher than the data suggests. As noted in Tables I11 and IV, a variety of methods were employed in the treatment of MPD and 12 of 18 patients received alkylating agents during the course of their disease. Only two patients were treated with "P, five underwent splenectomy, two had radiation therapy to the spleen and four cases received no chemotherapy or radiation. MPD patients are apparently predisposed to develop acute leukaemia and it is possible that alkylating agents also play a leukaemogenic role. However, the nature of the relationship between chemotherapeutic agents and the occurrence of leukaemia is not known. Some of the general features of acute leukaemia developing in patients with MPD are of interest. All 18 leukaemias were acute myeloblastic or myelomonocytic. Both in PVand AMM groups, leukaemia occurred in older adults and especially among males. The pre-leukaemic state was considerably longer in PV than AMM but the age at onset of leukaemia was similar in both groups. The long course of the MPD permitted repeated haematological and other studies. While no consistent findings were noted, a number of abnormalities seem to be important in separating out the pre-leukaemic cases. In several instances markedly dysplastic haemopoiesis was present months to years prior to the diagnosis of acute leukaemia. The development of the Pelger-Huet anomaly, a profound fall in previously elevated LAP scores, loss of MPA in segmented neutrophils, a marked rise in serum and urinary lysozyme at the onset of leukaemic phase, were all of special interest. These findings suggest a progressive disturbance in regulation of granulocytic maturation, possibly attributable to some form of somatic mutation. In this regard, three patients were noted to have aneuploidy prior to the diagnosis of leukaemia. In two cases, the abnormality involved the C chromosome. In no case of leukaemia was a complete remission obtained and the survival time was extremely short. Median survival was 3 weeks, with a range of 1-48 weeks; 12 of 18 cases died within 4 weeks. Poor response to chemotherapy and short survival are frequently observed in patients over 60 with acute myeloblastic leukaemia. In a recent analysis of 205 adult cases of AML followed over a 6 year period, we have noted that 98 of 205 patients were over 60 and, of
3 82
David S . Rosenthal and William C. Moloney
these, 50 had some preceding haematological disorder (Moloney & Rosenthal, unpublished data). These included 29 with refractory dysplastic anaemia, four with PV, five with aplastic anaemia and three with AMM. Patients with refractory, dysplastic anaemia shared many features noted in leukaemic MPD cases; they were older adults, predominantly males, had long pre-leukaemic states, responded poorly to chemotherapy and survival time was short. A consistent feature of these cases were the dysplastic changes found in the myeloid, erythroid and megakaryocytic precursors in the pre-leukaemic bone marrow. While the above observations do not explain the unfavourable course of AML in all older patients, interesting questions arise as to the nature of leukaemogenesis in this age group. It seems reasonable to postulate that, following an initial injury to a pleuripotential stem cell by viral, chemical, radiation, metabolic or immunological agents, the altered stem cell undergoes a prolonged latent period. During this time, due to additional exposure or possibly because of deficiencies of host maturation factors a variety of haematological disorders emerge. These include aplastic, metaplastic, hyperplastic, dysplastic and, in some instances, neoplastic disorders. The development of myeloblastic, myelomonocyticand erythromyelocytic leukaemias may be considered to be late events, possibly attributable to cell membrane changes, environmental factors or both. If this concept of leukaemogenesis is valid, it could explain the unfavourable course and poor response to chemotherapy in some older patients with AML. While aggressive chemotherapy might destroy leukaemic blast cells, no normal haematopoietic precursors would be available to repopulate the bone marrow. ACKNOWLEDGMENTS
Supported in part by National Institutes of Health, Division of Research Resources, GCRC Branch, Grant RR 00 888 and also the Nehemias G r i n Foundation. REFERENCES BERLIN, N.I. (1975)Diagnosis and classification of the polycythemias. Seminars in Hematology, Ia, 339. BUITON,L.N., ROSENTHAL, D.S., NATHAN,D.G. & MOLONBY, W.C. (1974)Computer evaluation of fmokinetics and p C r red cell survival in 37 patients with myeloid metaplasia. XIIth Intanational Society of Hematology, Jerusalem, Israel (Abstracts, p 163). DA~SHEK,W. (1951)Some speculations on the myeloprolifaativesyndromes. Blood, 6,372. LANDAW,S.A. (1976)Acute leukemia in polycythemia Vera. Seminars in Hematology, 13, 33. LAWRENCB, J.H., Wm-, H.S. & DONALD, W.G. (1969)Leukemia in polycythemia ven: relationship to splenic myeloid metaplasia and therapeutic radiation dose. Annals of Internal Medicine, 70, 763. LASZLO, J.(1975)Myeloproliferative disorders (MDP): myelofibrosis, myelosderosis, extramedullary hcmatopoiesis, undifferentiated MPD, and hemorrhagic thrombocythemia. Seminars in Hematology, 12, 409. McNm, B.J.,HOLMAN,B.L., BUITON,L.N. & ROSENTHAL, D.S. (1974)The use of indium chloride
scintigraphy in patients with myelofibrosis. Journal of Nuclear Medicine, 15, 647.
MOLONEY, W.C., MCP~IB~SON, K. & FLIBGBLMAN, L. (1960)Estuase activity in leukocytes demonstrated by the use of naphthol AS-D chloracetate substrate. Journal ofHistology and Cytochemistry, 8, 200. ROSBNTHAL, D.S. & MOLONEY, W.C. (1969)Myeloid metaplasia: a study of98 cases. Postgraduate Medicine, 46,136. S~vmts~apr, M.D. & L m w , J.W. (1969)Causes of death in agnogenic myeloid metaplasia. Mayo Clinic Proceedings, 4, 36. SKARIN.A.T., ~ Z U O Y. , & MOLONBY, W.C.(1972) Muramidase in myeloprolifaative disorders terd a t i n g in acute leukemia. Cancer, 19, 1336. W m .H.P. & BLOCK, M.H. (1971)The natural history of agnogenic myeloid metaplasia (AMM) and a critical evaluation of its relationship with the myeloproliferative syndrome. Medicine, 50, 3 57. WASSHBMAN, L.R (1954) Polycythemia Vera-its course and treatment: relation to myeloid metaplasia and leukemia. Bulletin of the New York Academy ofMedicine, 30, 343.
