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i 035
Case Report “
‘
:.:
‘.
‘
Mucormycosis of the Cuboid R. Chaudhuri,1
B. McKeown,1
Mucormycosis is infection known to pecially those with diseases, and renal
ebral,
Osteomyelitis Causing Avascular Bone: MR Imaging Findings
although
D. Harrington,2
R. J. Hay,3 J. B. Bingham,1
an uncommon but highly invasive fungal affect immunocompromised patients, esdiabetes mellitus, hematologic malignant failure. The most usual form is rhinocer-
it can have
abscess
foot
the
intestinal, disseminated, or cutaneous manifestations [i ]. We report a case of a renal transplantation patient who had pain and swelling in
diately
remote
of
fungal
of bowel
monas thema
perforation sepsis.
due
While
developed
he was
track
to cytomegalovirus
he
was
in the lateral
hospitalized,
aspect
Received March 1 6, 1 992; accepted 1 Department of Radiology, Division
admitted
for treatment
infection
and
pain,
swelling,
of his right foot.
after revision of Radiological
from
the
cuboid
tration
of
hyperemic
short
AJR 159:1035-1037,
November
1992 0361-803X/92/1595-1
and raised fungal
abscess
lesions
a clinical
growth
was
imme-
showed
no
suspicion
obtained
on
were normal apart from and a lucency corresponding to a
to the skin.
patient
was
No bone
referred
for
abnormality
was
scintigraphy
and
The radionuclide bone scan, (MOP), showed intense radiobone on equilibrium and static
showed
low
signal
on the
Ti -weighted
soft
tissues
dimeglumine (Fig.
1 0).
(0.1 Signal
mmol/kg)
intensity
except was
(500/
affecting only after adminishigh
in the on
the
(STIR) image (i 800/30/i 50 [TRITE/TI]) and in the surrounding soft tissues (Fig.
1 E).
Surgical
exploration
and biopsy
of the cuboid
bone
were
under-
taken. The subcutaneous tissues were infarcted with pus formation. Pseudomonas was cultured from the soft tissues. Results of the bone biopsy showed extensive necrosis of trabeculae and the marrow
ery-
St. Thomas
SE1 9AT,
St. Thomas
035 0 American
bone The
TI inversion recovery in the affected bone
both
Hospital,
St., London
three
of the foot
thickening
gadopentetate
St., London
of Trauma
Hospital,
a further
last
with a surrounding rim of lower intensity, bone (Fig. 1C). No enhancement occurred
of Dermatology,
Guy’s
no
and
uptake (Fig.
Department
St. Thomas
The
image
Department
Surgery,
bone,
inflammation
although
i A).
images
4
Hospital,
of Pseudomo-
1 B). MR
3
Guy’s
a culture
phases, with a large central area devoid of radionuclide
of Renal Medicine, Guy’s Hospital, St. Thomas St., London SE1 9RT, United Kingdom. and Orthopaedic
cuboid malleolus.
the cuboid (Fig.
20 [TRITE])
A soft-tissue
May 18, 1992. Sciences, Guy’s
the
lateral
soft-tissue
Department
2
yielding
MR imaging to exclude osteomyelitis. using “Tc-methylene diphosphonate nuclide uptake surrounding the cuboid
Pseudoand
site,
on plain radiographs
extensive
.
transplantation,
from the
infection,
Findings
causing
A 63-year-old man with polycystic kidney disease was treated with continuous ambulatory peritoneal dialysis for 8 months before receiving his first cadaveric renal transplant in June i 991 The onset of graft function was delayed for 6 weeks because of acute tubular necrosis and mild rejection. Initial immunosuppression was with prednisolone, azathioprine, and antilymphocyte globulin, which was given for i 0 days. Cyclosporin was started after the course of antilymphocyte globulin had been completed. No further episodes of rejection occurred, and his plasma creatinine level fell to about 200 mol/l. He was never neutropenic. after
this
culture.
Case Report
months
from
of surrounding
discernible
Three
drained
above
evidence
osteomyelitis To our knowl-
edge, this is the first description of mucormycosis osteomyelitis and avascular necrosis.
and J. D. Spencer
nas. We noted subsequent development of two fistulous tracks from the cuboid bone to the skin, which did not communicate with each other, as well as two other superficial abscesses on the dorsum of
pulmonary,
the foot and was found to have mucormycosis causing avascular necrosis of the cuboid bone.
was
Necrosis
United
United
Kingdom.
St., London
Roentgen
SE1 9AT,
SE1 9AT,
Ray Society
United
Kingdom.
Kingdom.
Downloaded from www.ajronline.org by 98.230.152.103 on 02/03/15 from IP address 98.230.152.103. Copyright ARRS. For personal use only; all rights reserved
i 036
CHAUDHURI
ET AL.
AJR:159,
November
1992
Fig. 1.-A, Plain radiograph of right foot shows normal appearance of cuboid bone with soft-tissue corresponding to track (arrow). B, Scintigram of lateral aspect of right foot shows central area of no radionuclide uptake (arrow) over bone, surrounded by a rim of high radionuclide uptake. C, Sagittal Ti-weighted MR Image of right foot shows low signal within cuboid bone with a rim of lower intensity (arrow). D, Axial contrast-enhanced MR Image through cuboid bone shows no enhancement of bone. Track to
defect cuboid
signal skin is
well visualized. STIR MR image shows high signal In cuboid bone (arrow)
E, Coronal
space with a predominantly acute inflammatory cellular infiltrate and numerous broad aseptate fungal hyphae having the typical morphologic appearance of mucormycosis. A zygomycete fungus, Rhizopus rhizopodoformis, was subsequently grown on culture. The cuboid bone was excised, the wound was debrided, and IV amphotericin was administered for 4 weeks. The patient mad a good recovery and was
well with
discharged
a functioning renal transplant.
soft tissues
in right foot.
was an inpatient on the same ward as our patient. It is, however, surprising that, if infection had been transmitted by inhalation,
no rhinocerebral
disease
or evidence
of dissemi-
nated mucormycosis infection occurred other than in the foot of our patient. It remains possible that secondary infection occurred through the initial abscess drainage site from airborne spores, but the fungus was never cultured from this site. This fungus causes tissue ischemia and
Discussion
and adjacent
invasion of blood vessels, leading hemorrhagic infarction depending
to on
Mucormycosis is a fungus of the class Zygomycetes, family Mucoraceae, and usually of the genera Rhizopus, Rhizomucot, orAbsidia. These fungi are ubiquitous in the environment, and, it has been said, in hospital wards, but environmental cultures taken regularly throughout a 10-year period in another institution [2] have seldom yielded the organism found in this case, Rhizopus rhizopodoformis. Patients particularly at risk for infection with this agent are those who are diabetic
arterial or venous involvement, and an intense inflammatory response. Isolated cuboid bone involvement with total avascular necrosis suggests loss of periosteal and nutrient arterial supply or diffuse central venous occlusion. As it spreads through perivascular spaces, bone destruction is an uncommon and late finding in rhinocerebral disease even when the
or immunocompromised,
ings. This patient was referred for scintigraphy and MR imaging because the clinical presentation was of cellulitis, and under-
roids,
hyperglycemia,
tation
patients),
whether
from
antirejection
or neutropenia
high
therapy [3].
The
doses
of ste-
(as in transplaninfection
has been
surrounding
are reflected
tissues
are extensively
involved.
in the radiographic,
These
scintigraphic,
features
and MR find-
reported in patients undergoing hemodialysis who were receiving desfemoxamine for iron overload [4]. Transmission is usually by inhalation or by direct invasion of the bowel in
lying osteomyelitis radionuclide
activity
malnutrition. Skin and subcutaneous tissues subjected thermal burns and nosocomial infections have become
appearance
in this case was not that of osteomyelitis,
fected screening
after application of dressing
of contaminated packs
in this
dressings case
to in-
[2, 5], but
did not show
any
evidence of mucormycosis infection. It is of particular interest that another patient with renal failure who had extensive rhinocerebral mucormycosis, diagnosed 3 months previously,
scintigraphy
would
that of avascular
was suspected. In osteomyelitis, bone be expected to show a focal increase in in the affected necrosis.
The
bone.
normal
The
scintigraphic
or reactive
bone
but ad-
jacent to the ischemic region showed increased radionuclide uptake in contrast to the lack of uptake in the central avascular portion of bone. This is compatible with the normal radiographic findings in early avascular necrosis as the mineral content of the bone is preserved while the cellular elements
Downloaded from www.ajronline.org by 98.230.152.103 on 02/03/15 from IP address 98.230.152.103. Copyright ARRS. For personal use only; all rights reserved
AJA:i59,
November 1992
MR OF MUCORMYCOSIS
in the marrow are affected by vascular occlusion [6], although with such marked scintigraphic findings, it is surprising that no evidence of osteoporosis was seen. MR imaging is said to be more sensitive and specific than mTc-MDP bone scintigraphy [7] in distinguishing between soft-tissue cellulitis, abscess, osteomyelitis, and avascular necrosis because of its increased spatial resolution. Low signal on the Ti-weighted image affected only the cuboid bone, suggesting a decrease in marrow fat and an increase in water content, with no enhancement after administration of gadopentetate dimeglumine except in the hyperemic soft tissues. The high signal intensity on the STIR image both in the affected bone and in the soft tissues reflects a high water content, as occurs with hyperemia, edema, or inflammation, and would be compatible with osteomyelitis and noninfectious inflammatory conditions as well as early avascular necrosis [7, 8]. However, a rim of low signal intensity also was present around the cuboid bone on the Ti-weighted image, which is consistent with class C avascular necrosis as described by Mitchell et al. [8] and does not occur in osteomyelitis unless it is long-standing. The different patterns described reflect the evolution of osteonecrosis, of which osteomyelitis can be the
cause, and depend
on the signal changes
due to the amount
of marrow fat, blood, water, and fibrosis present; other than with class C avascular necrosis, osteomyelitis is usually easily distinguished from avascular necrosis.
OSTEOMYELITIS
1037
AND AVN
Mucormycosis has previously been associated with a high mortality rate. In this case, the scintigraphic and MR imaging studies were critical in the diagnosis of avascular necrosis. Owing to the rapid diagnosis, appropriate surgery and therapy could be offered to our patient. Nonetheless, the excellent and rapid response to treatment in this case is unusual in this disease. REFERENCES 1 . Hammer recipient.
GS, Bottone EJ, Hirschman SZ. Mucormycosis Am J Clin Pathol 1975;64:389-398
2. Gartenberg G, Bottone mucormycosis (Rhizopus
EJ, Keusch GT, Weitzman
in a transplant
I. Hospital-acquired
rhizopodiformis) of skin and subcutaneous tismycology and treatment. N EngI J Med i978;299:
sue: epidemiology, 1115-1118 3. Anderson RJ, Schafer LA, Olin OB, Eickhoff TC. Infectious risk factors in the immunosuppressed host. Am J Med 1973;54:453-460 4, Boelaert JA, Fenves AZ, Cobum JW. Mucormycosis among patients on dialysis (letter). N EngI J Med i989;321 :190-1 91 5. Hammond DE, Winkelmann AK. Cutaneous phycomycosis: report of three cases with identification ofRhizopus. Arch Dermatol 1979;1 15:990-992
6. Greyson NO. Radionuclide eds. Diagnostic
imaging,
1535-1547 7. Unger E, Moldofsky osteomyelitis
bone scanning. 1st ed. New
P, Gatenby
by MR imaging.
AiR
York:
In: Grainger Churchill
A, Hartz W, Broder
AG, Allison OJ,
Livingstone,
1986:
G. Diagnosis
of
1988;150:605-610
8. Mitchell DG, Aao VM, Dalinka MK, et al. Femoral head avascular necrosis: correlation of MR imaging, radiographic staging, radionuclide imaging, and clinical findings. Radiology 1987;162:709-715
Downloaded from www.ajronline.org by 98.230.152.103 on 02/03/15 from IP address 98.230.152.103. Copyright ARRS. For personal use only; all rights reserved
i 038
Case
Rapid Growth
of Femoral
J. P. Crabbe,1
W. Martel,1
Herniation
pit of the femoral
Herniation
fewer
proved
neck
herniation
than i4 months.
important
is a common,
pit more
In order
to recognize
that
in size to i 7 X 14 mm and had become
benign
than
doubled
to avoid misdiagnosis,
such
rapid
growth
in
it is
of this benign
lesion is possible. Case Report A
55-year-old was
woman who had had pain in the left hip for several referred
to the
Section
of Orthopaedic
Surgery
for
evaluation. The clinical diagnosis at that time was left-sided ischial bursitis, and findings on the initial radiographs and all subsequent radiologic studies of the left hip were normal. However, incidentally noted
on the initial
radiographs
of the pelvis
and hips
was
a well-
defined, 9 x 10 mm lucent lesion, with sclerotic margins, in the right femoral neck (Fig. 1A). The patient had not had any signs or symptoms related to the right hip. At this time,
the diagnosis
made, but osteoid osteoma Two
months
of a probable
was considered
after the initial plain films,
herniation
pit was
up for a further
radiograph
At that time,
bone scan was
obtained (Fig. 1D). This showed normal flow and blood-pool phases, but delayed images revealed a focal region of abnormally increased uptake of radionuclide within the right femoral neck, corresponding to the lesion seen on radiographs. The lesion was thought to be benign, most likely a hemiation pit, but it was decided to do follow-up studies. A radiograph obtained 8 months after initial presentation showed that the lesion had increased Received
AJR
April
1
Department
2
Section
1 5, 1992;
of Radiology,
of Orthopaedic
159:1038-1040,
accepted
November
after revision
University
of Michigan
1992 0361 -803X/92/l
after
initial
Throughout relative
this
to the
time
right
hip.
the The
patient lesion
had
was
still
remained thought
asymptomatic
with a herniation pit, but because of the rapid increase in size, CT scans and MR images were obtained (Figs. 1E-1 H). CT scans showed a well-defined lesion of soft-tissue attenuation, with sclerotic margins, on the anterior surface of the femoral neck. The lesion had a cortical roof and a focal perforation 1 mm in diameter. MA images
showed a lesion that had uniformly low signal on Ti -weighted images and no significant enhancement after administration of contrast material. On T2-weighted intensity. this
time,
the
images, imaging
the lesion was of uniformly characteristics
were
high signal
considered
typical
for an enlarging, but otherwise unremarkable, hemiation pit. Despite the benign prognosis, the patient decided she wanted a biopsy of the lesion; this was done 14 months after her initial presentation. The lesion was resected by using a CORB biopsy needle (Zimmer Inc. , Warsaw, IN) and a pituitary rongeur. Macroscopically, the lesion
consisted of “slimy gray-white tissue.” Histologic examination showed a dense fibrous connective tissue with poorly defined foci, which were of looser texture and myxoid appearance. Fragments of cartiIage, bone, and fibrinous material also were present.
Discussion
A herniation “reaction
area,”
pit of the femoral
neck arises in relation to the
an area of sclerotic
bone,
covered
by collag-
enous tissue and neocartilage, present in the anterolateral region of the upper femoral neck in most adults [2]. lngrowth of these fibrous and cartilaginous elements occurs through a perforation
in the
subcortical
location
1500 E. Medical C American
pres-
to be consistent
cortex; to form
these the
tissues
then
radiographically
expand
Roentgen
Center
Or., Ann Arbor,
Ray Society
Ml 48109.
in a
identifiable
1500 E. Medical Center Or., Ann Arbor, Ml 48109. Address reprint requests to W. Martel.
Hospitals,
595-1038
14 months
(Fig. 1 B).
and another
i C).
May 1 5, 1992.
University of Michigan Hospitals,
Surgery,
was obtained.
lobulated
6 months,
entation, the lesion had increased in size to 23 x 16 mm; thin sclerotic margins were still present, but the contour was more lobulated (Fig.
as a less likely possibility.
a triple-phase
slightly
The lesion was followed
At
months
Pit
and L. S. Matthews2
entity that was first formally characterized by Pitt et al. in i 982 [1 1. The lesion is seen as a small rounded radiolucency, with a thin sclerotic margin, situated on the anterior surface of the femoral neck. In their original paper, Pitt et al. described two cases in which herniation pits increased in size, one during a 6-year period in a ballerina and the other during a 9year period in an avid jogger. However, to our knowledge, no reports of more rapid growth of a herniation pit have been presented since that time. We present a case in which the linear dimensions of a pathologically
Report
i 035
Case Report “
‘
:.:
‘.
‘
Mucormycosis of the Cuboid R. Chaudhuri,1
B. McKeown,1
Mucormycosis is infection known to pecially those with diseases, and renal
ebral,
Osteomyelitis Causing Avascular Bone: MR Imaging Findings
although
D. Harrington,2
R. J. Hay,3 J. B. Bingham,1
an uncommon but highly invasive fungal affect immunocompromised patients, esdiabetes mellitus, hematologic malignant failure. The most usual form is rhinocer-
it can have
abscess
foot
the
intestinal, disseminated, or cutaneous manifestations [i ]. We report a case of a renal transplantation patient who had pain and swelling in
diately
remote
of
fungal
of bowel
monas thema
perforation sepsis.
due
While
developed
he was
track
to cytomegalovirus
he
was
in the lateral
hospitalized,
aspect
Received March 1 6, 1 992; accepted 1 Department of Radiology, Division
admitted
for treatment
infection
and
pain,
swelling,
of his right foot.
after revision of Radiological
from
the
cuboid
tration
of
hyperemic
short
AJR 159:1035-1037,
November
1992 0361-803X/92/1595-1
and raised fungal
abscess
lesions
a clinical
growth
was
imme-
showed
no
suspicion
obtained
on
were normal apart from and a lucency corresponding to a
to the skin.
patient
was
No bone
referred
for
abnormality
was
scintigraphy
and
The radionuclide bone scan, (MOP), showed intense radiobone on equilibrium and static
showed
low
signal
on the
Ti -weighted
soft
tissues
dimeglumine (Fig.
1 0).
(0.1 Signal
mmol/kg)
intensity
except was
(500/
affecting only after adminishigh
in the on
the
(STIR) image (i 800/30/i 50 [TRITE/TI]) and in the surrounding soft tissues (Fig.
1 E).
Surgical
exploration
and biopsy
of the cuboid
bone
were
under-
taken. The subcutaneous tissues were infarcted with pus formation. Pseudomonas was cultured from the soft tissues. Results of the bone biopsy showed extensive necrosis of trabeculae and the marrow
ery-
St. Thomas
SE1 9AT,
St. Thomas
035 0 American
bone The
TI inversion recovery in the affected bone
both
Hospital,
St., London
three
of the foot
thickening
gadopentetate
St., London
of Trauma
Hospital,
a further
last
with a surrounding rim of lower intensity, bone (Fig. 1C). No enhancement occurred
of Dermatology,
Guy’s
no
and
uptake (Fig.
Department
St. Thomas
The
image
Department
Surgery,
bone,
inflammation
although
i A).
images
4
Hospital,
of Pseudomo-
1 B). MR
3
Guy’s
a culture
phases, with a large central area devoid of radionuclide
of Renal Medicine, Guy’s Hospital, St. Thomas St., London SE1 9RT, United Kingdom. and Orthopaedic
cuboid malleolus.
the cuboid (Fig.
20 [TRITE])
A soft-tissue
May 18, 1992. Sciences, Guy’s
the
lateral
soft-tissue
Department
2
yielding
MR imaging to exclude osteomyelitis. using “Tc-methylene diphosphonate nuclide uptake surrounding the cuboid
Pseudoand
site,
on plain radiographs
extensive
.
transplantation,
from the
infection,
Findings
causing
A 63-year-old man with polycystic kidney disease was treated with continuous ambulatory peritoneal dialysis for 8 months before receiving his first cadaveric renal transplant in June i 991 The onset of graft function was delayed for 6 weeks because of acute tubular necrosis and mild rejection. Initial immunosuppression was with prednisolone, azathioprine, and antilymphocyte globulin, which was given for i 0 days. Cyclosporin was started after the course of antilymphocyte globulin had been completed. No further episodes of rejection occurred, and his plasma creatinine level fell to about 200 mol/l. He was never neutropenic. after
this
culture.
Case Report
months
from
of surrounding
discernible
Three
drained
above
evidence
osteomyelitis To our knowl-
edge, this is the first description of mucormycosis osteomyelitis and avascular necrosis.
and J. D. Spencer
nas. We noted subsequent development of two fistulous tracks from the cuboid bone to the skin, which did not communicate with each other, as well as two other superficial abscesses on the dorsum of
pulmonary,
the foot and was found to have mucormycosis causing avascular necrosis of the cuboid bone.
was
Necrosis
United
United
Kingdom.
St., London
Roentgen
SE1 9AT,
SE1 9AT,
Ray Society
United
Kingdom.
Kingdom.
Downloaded from www.ajronline.org by 98.230.152.103 on 02/03/15 from IP address 98.230.152.103. Copyright ARRS. For personal use only; all rights reserved
i 036
CHAUDHURI
ET AL.
AJR:159,
November
1992
Fig. 1.-A, Plain radiograph of right foot shows normal appearance of cuboid bone with soft-tissue corresponding to track (arrow). B, Scintigram of lateral aspect of right foot shows central area of no radionuclide uptake (arrow) over bone, surrounded by a rim of high radionuclide uptake. C, Sagittal Ti-weighted MR Image of right foot shows low signal within cuboid bone with a rim of lower intensity (arrow). D, Axial contrast-enhanced MR Image through cuboid bone shows no enhancement of bone. Track to
defect cuboid
signal skin is
well visualized. STIR MR image shows high signal In cuboid bone (arrow)
E, Coronal
space with a predominantly acute inflammatory cellular infiltrate and numerous broad aseptate fungal hyphae having the typical morphologic appearance of mucormycosis. A zygomycete fungus, Rhizopus rhizopodoformis, was subsequently grown on culture. The cuboid bone was excised, the wound was debrided, and IV amphotericin was administered for 4 weeks. The patient mad a good recovery and was
well with
discharged
a functioning renal transplant.
soft tissues
in right foot.
was an inpatient on the same ward as our patient. It is, however, surprising that, if infection had been transmitted by inhalation,
no rhinocerebral
disease
or evidence
of dissemi-
nated mucormycosis infection occurred other than in the foot of our patient. It remains possible that secondary infection occurred through the initial abscess drainage site from airborne spores, but the fungus was never cultured from this site. This fungus causes tissue ischemia and
Discussion
and adjacent
invasion of blood vessels, leading hemorrhagic infarction depending
to on
Mucormycosis is a fungus of the class Zygomycetes, family Mucoraceae, and usually of the genera Rhizopus, Rhizomucot, orAbsidia. These fungi are ubiquitous in the environment, and, it has been said, in hospital wards, but environmental cultures taken regularly throughout a 10-year period in another institution [2] have seldom yielded the organism found in this case, Rhizopus rhizopodoformis. Patients particularly at risk for infection with this agent are those who are diabetic
arterial or venous involvement, and an intense inflammatory response. Isolated cuboid bone involvement with total avascular necrosis suggests loss of periosteal and nutrient arterial supply or diffuse central venous occlusion. As it spreads through perivascular spaces, bone destruction is an uncommon and late finding in rhinocerebral disease even when the
or immunocompromised,
ings. This patient was referred for scintigraphy and MR imaging because the clinical presentation was of cellulitis, and under-
roids,
hyperglycemia,
tation
patients),
whether
from
antirejection
or neutropenia
high
therapy [3].
The
doses
of ste-
(as in transplaninfection
has been
surrounding
are reflected
tissues
are extensively
involved.
in the radiographic,
These
scintigraphic,
features
and MR find-
reported in patients undergoing hemodialysis who were receiving desfemoxamine for iron overload [4]. Transmission is usually by inhalation or by direct invasion of the bowel in
lying osteomyelitis radionuclide
activity
malnutrition. Skin and subcutaneous tissues subjected thermal burns and nosocomial infections have become
appearance
in this case was not that of osteomyelitis,
fected screening
after application of dressing
of contaminated packs
in this
dressings case
to in-
[2, 5], but
did not show
any
evidence of mucormycosis infection. It is of particular interest that another patient with renal failure who had extensive rhinocerebral mucormycosis, diagnosed 3 months previously,
scintigraphy
would
that of avascular
was suspected. In osteomyelitis, bone be expected to show a focal increase in in the affected necrosis.
The
bone.
normal
The
scintigraphic
or reactive
bone
but ad-
jacent to the ischemic region showed increased radionuclide uptake in contrast to the lack of uptake in the central avascular portion of bone. This is compatible with the normal radiographic findings in early avascular necrosis as the mineral content of the bone is preserved while the cellular elements
Downloaded from www.ajronline.org by 98.230.152.103 on 02/03/15 from IP address 98.230.152.103. Copyright ARRS. For personal use only; all rights reserved
AJA:i59,
November 1992
MR OF MUCORMYCOSIS
in the marrow are affected by vascular occlusion [6], although with such marked scintigraphic findings, it is surprising that no evidence of osteoporosis was seen. MR imaging is said to be more sensitive and specific than mTc-MDP bone scintigraphy [7] in distinguishing between soft-tissue cellulitis, abscess, osteomyelitis, and avascular necrosis because of its increased spatial resolution. Low signal on the Ti-weighted image affected only the cuboid bone, suggesting a decrease in marrow fat and an increase in water content, with no enhancement after administration of gadopentetate dimeglumine except in the hyperemic soft tissues. The high signal intensity on the STIR image both in the affected bone and in the soft tissues reflects a high water content, as occurs with hyperemia, edema, or inflammation, and would be compatible with osteomyelitis and noninfectious inflammatory conditions as well as early avascular necrosis [7, 8]. However, a rim of low signal intensity also was present around the cuboid bone on the Ti-weighted image, which is consistent with class C avascular necrosis as described by Mitchell et al. [8] and does not occur in osteomyelitis unless it is long-standing. The different patterns described reflect the evolution of osteonecrosis, of which osteomyelitis can be the
cause, and depend
on the signal changes
due to the amount
of marrow fat, blood, water, and fibrosis present; other than with class C avascular necrosis, osteomyelitis is usually easily distinguished from avascular necrosis.
OSTEOMYELITIS
1037
AND AVN
Mucormycosis has previously been associated with a high mortality rate. In this case, the scintigraphic and MR imaging studies were critical in the diagnosis of avascular necrosis. Owing to the rapid diagnosis, appropriate surgery and therapy could be offered to our patient. Nonetheless, the excellent and rapid response to treatment in this case is unusual in this disease. REFERENCES 1 . Hammer recipient.
GS, Bottone EJ, Hirschman SZ. Mucormycosis Am J Clin Pathol 1975;64:389-398
2. Gartenberg G, Bottone mucormycosis (Rhizopus
EJ, Keusch GT, Weitzman
in a transplant
I. Hospital-acquired
rhizopodiformis) of skin and subcutaneous tismycology and treatment. N EngI J Med i978;299:
sue: epidemiology, 1115-1118 3. Anderson RJ, Schafer LA, Olin OB, Eickhoff TC. Infectious risk factors in the immunosuppressed host. Am J Med 1973;54:453-460 4, Boelaert JA, Fenves AZ, Cobum JW. Mucormycosis among patients on dialysis (letter). N EngI J Med i989;321 :190-1 91 5. Hammond DE, Winkelmann AK. Cutaneous phycomycosis: report of three cases with identification ofRhizopus. Arch Dermatol 1979;1 15:990-992
6. Greyson NO. Radionuclide eds. Diagnostic
imaging,
1535-1547 7. Unger E, Moldofsky osteomyelitis
bone scanning. 1st ed. New
P, Gatenby
by MR imaging.
AiR
York:
In: Grainger Churchill
A, Hartz W, Broder
AG, Allison OJ,
Livingstone,
1986:
G. Diagnosis
of
1988;150:605-610
8. Mitchell DG, Aao VM, Dalinka MK, et al. Femoral head avascular necrosis: correlation of MR imaging, radiographic staging, radionuclide imaging, and clinical findings. Radiology 1987;162:709-715
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i 038
Case
Rapid Growth
of Femoral
J. P. Crabbe,1
W. Martel,1
Herniation
pit of the femoral
Herniation
fewer
proved
neck
herniation
than i4 months.
important
is a common,
pit more
In order
to recognize
that
in size to i 7 X 14 mm and had become
benign
than
doubled
to avoid misdiagnosis,
such
rapid
growth
in
it is
of this benign
lesion is possible. Case Report A
55-year-old was
woman who had had pain in the left hip for several referred
to the
Section
of Orthopaedic
Surgery
for
evaluation. The clinical diagnosis at that time was left-sided ischial bursitis, and findings on the initial radiographs and all subsequent radiologic studies of the left hip were normal. However, incidentally noted
on the initial
radiographs
of the pelvis
and hips
was
a well-
defined, 9 x 10 mm lucent lesion, with sclerotic margins, in the right femoral neck (Fig. 1A). The patient had not had any signs or symptoms related to the right hip. At this time,
the diagnosis
made, but osteoid osteoma Two
months
of a probable
was considered
after the initial plain films,
herniation
pit was
up for a further
radiograph
At that time,
bone scan was
obtained (Fig. 1D). This showed normal flow and blood-pool phases, but delayed images revealed a focal region of abnormally increased uptake of radionuclide within the right femoral neck, corresponding to the lesion seen on radiographs. The lesion was thought to be benign, most likely a hemiation pit, but it was decided to do follow-up studies. A radiograph obtained 8 months after initial presentation showed that the lesion had increased Received
AJR
April
1
Department
2
Section
1 5, 1992;
of Radiology,
of Orthopaedic
159:1038-1040,
accepted
November
after revision
University
of Michigan
1992 0361 -803X/92/l
after
initial
Throughout relative
this
to the
time
right
hip.
the The
patient lesion
had
was
still
remained thought
asymptomatic
with a herniation pit, but because of the rapid increase in size, CT scans and MR images were obtained (Figs. 1E-1 H). CT scans showed a well-defined lesion of soft-tissue attenuation, with sclerotic margins, on the anterior surface of the femoral neck. The lesion had a cortical roof and a focal perforation 1 mm in diameter. MA images
showed a lesion that had uniformly low signal on Ti -weighted images and no significant enhancement after administration of contrast material. On T2-weighted intensity. this
time,
the
images, imaging
the lesion was of uniformly characteristics
were
high signal
considered
typical
for an enlarging, but otherwise unremarkable, hemiation pit. Despite the benign prognosis, the patient decided she wanted a biopsy of the lesion; this was done 14 months after her initial presentation. The lesion was resected by using a CORB biopsy needle (Zimmer Inc. , Warsaw, IN) and a pituitary rongeur. Macroscopically, the lesion
consisted of “slimy gray-white tissue.” Histologic examination showed a dense fibrous connective tissue with poorly defined foci, which were of looser texture and myxoid appearance. Fragments of cartiIage, bone, and fibrinous material also were present.
Discussion
A herniation “reaction
area,”
pit of the femoral
neck arises in relation to the
an area of sclerotic
bone,
covered
by collag-
enous tissue and neocartilage, present in the anterolateral region of the upper femoral neck in most adults [2]. lngrowth of these fibrous and cartilaginous elements occurs through a perforation
in the
subcortical
location
1500 E. Medical C American
pres-
to be consistent
cortex; to form
these the
tissues
then
radiographically
expand
Roentgen
Center
Or., Ann Arbor,
Ray Society
Ml 48109.
in a
identifiable
1500 E. Medical Center Or., Ann Arbor, Ml 48109. Address reprint requests to W. Martel.
Hospitals,
595-1038
14 months
(Fig. 1 B).
and another
i C).
May 1 5, 1992.
University of Michigan Hospitals,
Surgery,
was obtained.
lobulated
6 months,
entation, the lesion had increased in size to 23 x 16 mm; thin sclerotic margins were still present, but the contour was more lobulated (Fig.
as a less likely possibility.
a triple-phase
slightly
The lesion was followed
At
months
Pit
and L. S. Matthews2
entity that was first formally characterized by Pitt et al. in i 982 [1 1. The lesion is seen as a small rounded radiolucency, with a thin sclerotic margin, situated on the anterior surface of the femoral neck. In their original paper, Pitt et al. described two cases in which herniation pits increased in size, one during a 6-year period in a ballerina and the other during a 9year period in an avid jogger. However, to our knowledge, no reports of more rapid growth of a herniation pit have been presented since that time. We present a case in which the linear dimensions of a pathologically
Report
