Path. Res. Pract. 188, 791-796 (1992)
T eaching Cases
"Solid" Variant of Aneurysma! Bane eyst G. Edel, A. Roessner, S. Blasius Gerhard-Oomagk-Institut für Pathologie der Universität Münster, Münster, FRG
R. Erlemann Institut für Klinische Radiologie der Universität Münster, Münster, FRG
SUMMARY A case of the so-called "solid" variant of aneurysmal bone cyst is reported. A 12-year-old girl with a few weeks' history of backache presented with a tender palpable mass located thoraco-spinal in the back at Th 3. Radiologically, the lesion was consistent with conventional aneurysmal bone cyst. Morphologically, it showed fibroblastic, fibrohistiocytic, fibromyxoid, osteoclastic and osteoblastic components as weil as small aneurysmal sinusoids. Based on four other weil documented cases, the clinico-pathological features and the differential diagnostical problems are discussed.
Introduction Primary aneurysmal bone cyst (ABC), a benign tumorlike lesion, was first described by Jaffe and Lichtenstein l4 in 1942. Although it may occur at any age, about 85% of all cases are seen in patients under the age of 20 5,9,2°. The lesion has been observed in various sites of the long tubular bones and the spineS, 9,16,20,25. ABC shows a preference of the female sex. Its most important histological features are multiloculated cyst-like spaces of varying size, often filled with blood, and separated by fibrous septa containing histiocytes, osteoclast-like giant cells and osteoid 5,9,16,20,25. Occasionally these spaces are lined by a single layer of flattened cells of fibroblastic and histiocytic origin I. In solid areas of ABC fibrous tissue, a lacework of osteoid, newly formed trabeculae and many osteoclast-like giant cells may be predominant9, 10,20,25. A special variant of ABC was first described by Sanerkin and co-workers in 1983 24 • They reported four cases of an unusual intraosseous lesion with fibroblastic, osteoclastic, osteoblastic, aneurysmal and fibromyxoid elements, classifying it as "solid" variant of aneurysmal bone cyst ("solid" ABC). All lesions were observed in children, three were located in the spine, one in the ethmoid q.nd orbital region. In the present study, we report another solid lesion recently observed in the spine. © 1992 by Gustav Fischer Verlag, Stuttgart
Case Report A 12-year-old girl was admitted to hospital complaining about pain and backache, which had persisted for several weeks. On clinical examination, a tender palpable mass, localized in the thoraco-spinal part of the dorsum at Th 3, muscle spasm and a minor scoliosis were recorded, as weil as indications of spinal cord compression. Radiography revealed a purely lytic lesion which had destroyed the neural arch (Fig. 1). Magnetic resonance tomography outlined a huge mass within the posterior part of the spine, located within the posterior elements of Th 3 and Th 4. The lesion invaded the spinal canal, compressing the posterior arachnoidal space (Fig. 2). These radiological features were consistent with ABC. Therapy included excision and complete curettage, the postoperative course was uneventful. To our knowledge the patient is weil without recurrent disease three years after surgery. M.aterial and Methods The surgical specimens were fixed in 4% buffered formalin, decalcified in 10% EDTA solution and embedded in paraffin. 4-5 [!m sections were stained with hematoxylin (HE), elastica van Gieson (EVG) and periodic acid-Schiff (PAS). 0344-0338/92/0188-0791$3.50/0
792 . G. Edel et al.
Fig. 1. Radiograph showing destruction of the neural arch of Th 3 and erosion of the upper part of the neural arch ofTh 4. The lesion is purely osteolytic.
Results Histologieally the lesion comprised different tissue eomponents, the predominant elements being fibroblastie and fibro-histioeytie eeIls, sometimes arranged in a whorled pattern. Their nuclei were plump, but without anaplasia (Fig.3 ). Some normal mitotie figures were observed. In other p arts of the lesion, a fibro-m yxoid stroma with a loose array of spindle-shaped eells was established (Fig. 4). There were alsosmall foei with many osteoclast-like giant eells (Fig. 5), and sm all areas of osteoid and woven bone with a rim of aetivated osteoblasts (Fig. 6). FinaIly, we observed sma11 blood-fi11ed aneurysmal sinusoids, lined by a fibro-histioeytie stroma containing many osteoclast-like giant ee11s (Fig. 7 a, b). Final diagnosis was "solid " variant of aneurysmal bone eyst. Discussion Apparently, "solid" ABC is arare, tumor-like lesion of bone. To our knowledge, only 4 weIl doeumented ca ses
Fig. 2. In MRI, a huge soft tissue mass is seen within the posterior elements of Th 3 and Th 4. In Th 3 th e tumor extends into the spinal canal, compressing the posterior part of the subarachnoidal space.
have been published 24 until today. All patients were children between the ages of 5 and 13, three of them were boys and one a girl. Three lesions were loealized within the spine (Th 2, Th 7 and L 4), one was found in the right ethmoid bone and orbit. Our juvenile patient, a 12year-old girl, also had a spinalIesion at Th 3. The clinical symptoms - pain, loeal swelling, muscle spasm and signs of cord eompression - were similar to those deseribed by Sanerkin and eo-workers 24 in their doeumentation of spinalIesions (cases 3 and 4). Radiographie and MRI findings supported the diagnosis of ABC. In spinal ABCs, almost a11 reeorded lesions originate in the posterior elements of the vertebraeS,20,25,30; oeeasionaIly, a lateral part of one vertebral body isinvolved as weIl5,25,30. Up to 40% of spinal ABCs pass across the intervertebral spaee to another vertebra 10, 11 ,13,30. ABCs are lytie lesions with frequent osseous septa, showing a soft tissue mass surro unded b y athin ossified periosteal shelpo. Most benign tumors and tumor-like lesions of the spine are found exclusively within the posterior elements, without affeetion of the vertebral bod y5, 9,20, 25 . There are, however, two exeeptions: Osteoblastom as may affeet both the posterior
Solid Variant of Aneurysmal Bone eyst . 793
Fig.3. Solid stroma component with fibroblastic and fibrohistiocytic cells arranged in a whorled pattern with scattered mitotic figures suggesting a malignant tumor. HE, x 160.
Fig. 4. Fibromyxoid stroma component with loosely arranged spindie cells. HE, x 160.
arch and the body of the vertebra 19. Giant cell tumors usually originate from the body of the vertebra but can expand to the posterior elements 8,26. On the other hand, most malignant bone tumors are localized within the vertebral body, whereas chordomas may show involvement of both the body and neural arch 21 ,28. Few ABCs show radiographie growth patterns indicating a malignant tumor, such as complete destruction of the cortex, a "moth-eaten" boundary and a huge soft tissue mass 5 . Based on radiographie features alone, the differentiation of spinal ABC from osteoblastoma may be next to impossible, since these may be very similar5,20. Thus, careful histological examination is all the more necessary. In contrast, vertebral osteosarcomas show a predilection for the vertebral body, rarely extending into the posterior vertebral elements5, 11 , 20. Mirra 20 reported six further cases of "solid" ABC in his publication. However, only one of them is radiologically and histologically documented. The patient was a 40year-old woman with a_. lesion in the distal humerus. Radiologically an eccentric destruction of the bone with "blow-out" appearance and sharply circumscribed and
scalloped margins was seen. After reviewing his own collection of six cases Mirra 20 concluded that radiologie features of solid ABC are as variable as those described for conventional ABC. Sanerkin and co-workers 24 as well as Mirra 20 pointed out that, depending on the proliferative component, "solid" ABC may be histologically mi staken for other benign and malignant tumors and tumor-like lesions of bone, among them osteosarcoma and fibrosarcoma, osteoblastoma, giant cell tumor of bone, reparative giant cell granuloma, fibrous dysplasia and ossifying fibroma (osteofibrous dysplasia). In our opinion the lack of anaplasia in all tissue components of the presented case strongly argues against osteo- or fibrosarcoma. Typical, but no atypical mitotic figures were regularly observed in all cases of "solid" ABClO,24. The other entities cited above could be histologically ruled out as follows: Osteoblastoma, a common bone tumor in childhood, which often affects the spine5 ,9, lO, 20,2S, may sometimes show aneurysmal bone cyst-like cavities5,9. The main
794 . G. Edel er al.
Fig. 5. Focus wirh osteoelast-like giant cells resembling a gianr cell tumor. HE, X 160.
Fig. 6. Small areas of interlacing bone trabeculac with an osteoblastic rim in a capillary-rich fibrous stroma containing osteoelasts suspicious of osteoblastoma. HE, X 160.
histological elements of this tumor, however, are numerous interlacing trabeculae or small islands of osteoid bordered by rows of large osteoblasts, a great number of capillaries between the trabeculae and multinucleated giant cells S , 9, 10,20,25. Some of these features were indeed seen in our case, however, only in sm all areas. The predominant tissue component was of the fibroblastic type, which is never present in osteoblastoma 2o . The morphological differential diagnosis between "solid" ABC and giant cell tumor may be extremely difficult, especially when osteoclast-like giant cells are present in areas larger than 1 cm 20 • In our case, however, the foci of osteoclast-like giant cells had a diameter of less than 1 cm. Furthennore, in contrast to ABC, giant cell tumor of the spine almost entirely originates from the body of the vertebra and may secondarily affect the posterior arch 7- 10 ,J8,20,26, as mentioned before. In addition, this tumor hardly ever occurs in patients under the age of 15 5,7, 12, 18,20,23. Giant cell reparative granuloma 2, 3, 15, 17 mayaiso resemble solid areas of ABC and these two lesions may be related 6, 29. But giant cell reparative granuloma is known to
occur only in the skull, jaws, hand, foot and facial bones 2 ,3, 15, 17, 22,27, so this entity can be excluded, too. Fibrous dysplasia, which may sometimes show cystic degenerationS, 20, 25, can also be ruled out in the present case, since this lesion is characterized by a fibrous stroma with short or long curled spicules of wovenbone in bizzare configuration with no osteoblastic rimS,9,1O,20. These features could not be demonstrated in the present tumor. Ossifying fibroma (osteofibrous dysplasia) is also unlikely, occuring almost exclusively in the tibia and occasionally in the homolateral fibula 4,s. Cystic formation is uncommon in this type of lesion. As in case 4 published by Sanerkin and co-workers 24, we failed to detect any foci of degenerated calcifying fibromyxoid tissue with a "chondroid aura" 29, otherwise considered typical for conventional and "solid" ABO, 20, 24. Finally, conventional ABC was also unlikely in our case, because 110 large cyst-like spaces were seen. Nevertheless, we maintail1 the theory that ABC and "solid" ABC are closely related, due to their similarities regarding radiolog-
Solid Variant of Aneurysmal Bone Cyst . 795
Fig. 7. Small blood-filled typical aneurysmal sinusoids (a: HE, (b: HE, X 100).
X
40) lined by fibro-histiocytic cells and many osteoblast-like giant cells
ical features and morphological structures of the cystic walls. The clinical courses of our case and the other published cases were benign 20,24. Local recurrence is possible as with conventional ABC2o. Pathologists should become familiar with the "solid" variant of ABC because of the many possible diagnostic pitfalls which lie in this lesion. i
Acknowledgement Thc authors would like to thank Mrs. E. Griffiths for typing the manuscript.
References 1 Alles JU, Schulz A (1986) Immunocytochemical markers (endothelial and histiocytic) and ultrastructure of primary aneurysmal bone cyst. Hum Pathol 17: 39-45 2 Austin LT, Dahlin DC, Roger RQ (1959) Giant-cell rcparative granuloma and related conditions affecting the jaw-bones. Oral Surg12: 1285-1295
.1 Bhaskar SN, Bernier JL, Godby F (1959) Aneurysmal bone cyst and other giant celilesions of the jaws: Report of 104 cases. J Oral Surg Anesth Hosp D Serv 17: 30-41 4 Campanacci M, Laus M (1981) Osteofibrous dysplasia ofthe tibia and fibula. J Bone Joint Surg 63A: 367-375 5 Camp an ace i M (1990) Bone and Soft Tissue Tumors. Co-authors of soft tissue section: Bertoni F, Bacchini P, Aulo Gaggi Editore Bologna, Springer Verlag, Wien-New York 6 Dahlin DC (1967) Bone Tumors. Ed 2, Charles C Thomas Publ, Springfield, Illinois, USA 7 Dahlin DC, Cupps RE, Johnson EW (1970) Giant-cell tumor: A study of 195 cases. Cancer 25: 1061-1070 8 Dahlin DC (1977) Giant cell tumors of vertebrae above the sacrum. A review of 31 cases. Cancer 39: 1350-1356 9 Dahlin DC, Unni K (1986) Bone Tumors, General Aspects and Data Oll 8, 542 Cases. Ed 4, Charles C Thomas Publ, Springfield, Illinois, USA 10 Dominok GW, Knoch HG (1982) Knochengeschwülste und geschwulstähnliche Knochencrkrankungen. Gustav Fischer Verlag, Stuttgart 11 Erlemann R, Reiser M, Roessner A, Peters PE, Grundmann E (1987) Primäre Knochentumoren und tumorähnliche Läsionen der Wirbelsäule. Eine Analyse radiologischer Dignitätskriterien. RöFo 147: 131-137 12 Goldenberg RR, Campbell q, Bonfiglio M (1970) Giantcell tumor of bone: An analysis of two hundred and eighteen cases. J Bone Joint Surg 52A: 619-663
796 . G. Edel et al. 13 Hay MC, Paterson D, Taylor KF (1978) Aneurysmal bone eysts of the spine. J Bone Joint Surg 60B: 406-411 14 Jaffe HL, Liehtenstein L (1942) Solitary unieameral bone eyst with emphasis on the roentgen pieture, the pathologie appearanee, and the pathogenesis. Areh Surg 44: 1004-1025 15 Jaffe HL (1953) Giant-eell reparative granuloma; traumatie bone eyst, and fibrous (fibro-osseous) dysplasia of jawbones. Oral Surg 6: 159-175 16 Liehtenstein L (1977) Bone Tumors. Ed 5, CV Mosby, Saint Louis 17 Lorenzo JC, Dorfman HD (1980) Giant eell reparative granuloma of short tubular bones of the hands and feet. AmJ Surg Pathol 4: 551-563 18 MeGrath PJ (1972) Giant-eell tumour of bone: An analysis of fifty-two eases. J Bone Joint Surg 54B: 216-229 19 MeLeod RA, Dahlin DC, Beabout JW (1976) The speetrum of osteoblastoma. Am J Roentgenol126: 321-335 20 Mirra JM, in eollaboration with Pieei P, Gold RH (1989) Bone Tumors, Clinieal, Radiologie, and Pathologie Correlations. Vol. 1 and 2, Lea and Febiger, Philadelphia - London 21 Mulder JD, Poppe H, van Ronnen JR (1981) Primäre Knoehengesehwülste. In: Sehinz HR (Ed) Lehrbueh der Röntgendiagnostik, Bd 2/II. Thieme, Stuttgart-New York 22 Ratner V, Dorfman HD (1990) Giant-eell reparative granuloma of the hand and foot bones. Clin Orthop 260: 251-258
23 Sanerkin NG (1980) Malignaney, aggressiveness, and reeurrenee in giant-eell tumor of bone. Caneer 46: 1614-1649 14 Sanerkin NG, Mott MG, Roylanee J (1983) An unusual intraosseous lesion with fibroblastie, osteoclastie, osteoblastie, aneurysmal and fibromyxoid elements. "Solid" variant of aneurysmal bone eyst. Caneer 51: 2278-2286 15 Sehaehowiez F (1981) Tumors and Tumor-like Lesions of Bone and Joints. Springer Verlag, Ncw York-Heidelberg-Berlin 26 Sehwimer SE, Bassett LW, Maneuso AA, Mirra J, Dawson EG (1981) Giant eell tumor of the eervieothoraeie spine. Am J Roentgenol 136: 63-67 17 Sehwinn CP (1976) Differential diagnosis of giant-eell lesions of bone. In: Aekerman LV, Spjut HJ, Abell MR (Eds) Bone and Joints. The Williams and Wilkins Co, pp. 255-258. Baltimore 18 Subbarao K, Jaeobson HG (1979) Primary malignant neoplasms. Semin Roentgenol14: 44-57 19 Tillman BP, Dahlin DC, Lipscomb PR (1968) Aneurysmal bone eyst: An analysis of 95 eases. Maco Clin Proe 43: 478-495 30 Wilner D (1982) Radiology of Bone Tumors and Allied Disorders. Vol. 4, Saunders, Philadelphia
Reeeived June 10, 1991 . Aeeepted in revised form September 19, 1991
Key words: Bone tumors - Aneurysmal bone cyst - Solid variant - Spine tumors G. Edel, M.D., Gerhard-Domagk-Institut für Pathologie, Universität Münster, Domagkstr. 17, D-4400 Münster, FRG
Letters to the Case K. Unni Rochester, USA
The concept of 'solid' aneurysmal bone cyst (ABC) has gained acceptance among pathologists with a special interest in bone tumors since the original description by Sanerkin in 1981. However, this entity is still not widely known in general surgical pathology, orthopedic, and radiology circles. The manuscript by Edel and co-authors appropriately brings attention to this rare, but important entity. Some pathologists object to the term solid aneurysmal bone cyst rightly pointing out that this is an 'oxymoron'. This is true, of course, but the other term proposed for this entity 'giant cell reparative granuloma' is no better because the lesion is certainly not a granuloma. The term proposed by Sanerkin has the advantage of emphasizing the relationship of this lesion to Classic ABC as pointed out by Edel and co-authors. I prefer the designation solid ABC to giant cell
reparative granuloma. A more appropriate term might be giant cell reaction, a term used by Ackerman and Spjut to describe alesion of the sm all bones of the hands and feet, which has also been designated gianr cell granuloma. I agree with the authors that the clinical features and roentgenograms of solid ABC are nonspecific just as they are with more classical ABC. In a small percentage of cases of ABC the roentgenograms look very aggressive and mimic a malignancy. Good radiologists know that they cannot always distinguish ABC from neoplasms, especially telangiectatic osteosarcoma. One of the problems with the diagnosis of solid ABC is that grossly the lesion lacks the typical multicystic appearance that knowledgeable surgeons look for. However, it does not appear fleshy as a sarcoma would, but red and granular such as seen in histiocytosis X.
T eaching Cases
"Solid" Variant of Aneurysma! Bane eyst G. Edel, A. Roessner, S. Blasius Gerhard-Oomagk-Institut für Pathologie der Universität Münster, Münster, FRG
R. Erlemann Institut für Klinische Radiologie der Universität Münster, Münster, FRG
SUMMARY A case of the so-called "solid" variant of aneurysmal bone cyst is reported. A 12-year-old girl with a few weeks' history of backache presented with a tender palpable mass located thoraco-spinal in the back at Th 3. Radiologically, the lesion was consistent with conventional aneurysmal bone cyst. Morphologically, it showed fibroblastic, fibrohistiocytic, fibromyxoid, osteoclastic and osteoblastic components as weil as small aneurysmal sinusoids. Based on four other weil documented cases, the clinico-pathological features and the differential diagnostical problems are discussed.
Introduction Primary aneurysmal bone cyst (ABC), a benign tumorlike lesion, was first described by Jaffe and Lichtenstein l4 in 1942. Although it may occur at any age, about 85% of all cases are seen in patients under the age of 20 5,9,2°. The lesion has been observed in various sites of the long tubular bones and the spineS, 9,16,20,25. ABC shows a preference of the female sex. Its most important histological features are multiloculated cyst-like spaces of varying size, often filled with blood, and separated by fibrous septa containing histiocytes, osteoclast-like giant cells and osteoid 5,9,16,20,25. Occasionally these spaces are lined by a single layer of flattened cells of fibroblastic and histiocytic origin I. In solid areas of ABC fibrous tissue, a lacework of osteoid, newly formed trabeculae and many osteoclast-like giant cells may be predominant9, 10,20,25. A special variant of ABC was first described by Sanerkin and co-workers in 1983 24 • They reported four cases of an unusual intraosseous lesion with fibroblastic, osteoclastic, osteoblastic, aneurysmal and fibromyxoid elements, classifying it as "solid" variant of aneurysmal bone cyst ("solid" ABC). All lesions were observed in children, three were located in the spine, one in the ethmoid q.nd orbital region. In the present study, we report another solid lesion recently observed in the spine. © 1992 by Gustav Fischer Verlag, Stuttgart
Case Report A 12-year-old girl was admitted to hospital complaining about pain and backache, which had persisted for several weeks. On clinical examination, a tender palpable mass, localized in the thoraco-spinal part of the dorsum at Th 3, muscle spasm and a minor scoliosis were recorded, as weil as indications of spinal cord compression. Radiography revealed a purely lytic lesion which had destroyed the neural arch (Fig. 1). Magnetic resonance tomography outlined a huge mass within the posterior part of the spine, located within the posterior elements of Th 3 and Th 4. The lesion invaded the spinal canal, compressing the posterior arachnoidal space (Fig. 2). These radiological features were consistent with ABC. Therapy included excision and complete curettage, the postoperative course was uneventful. To our knowledge the patient is weil without recurrent disease three years after surgery. M.aterial and Methods The surgical specimens were fixed in 4% buffered formalin, decalcified in 10% EDTA solution and embedded in paraffin. 4-5 [!m sections were stained with hematoxylin (HE), elastica van Gieson (EVG) and periodic acid-Schiff (PAS). 0344-0338/92/0188-0791$3.50/0
792 . G. Edel et al.
Fig. 1. Radiograph showing destruction of the neural arch of Th 3 and erosion of the upper part of the neural arch ofTh 4. The lesion is purely osteolytic.
Results Histologieally the lesion comprised different tissue eomponents, the predominant elements being fibroblastie and fibro-histioeytie eeIls, sometimes arranged in a whorled pattern. Their nuclei were plump, but without anaplasia (Fig.3 ). Some normal mitotie figures were observed. In other p arts of the lesion, a fibro-m yxoid stroma with a loose array of spindle-shaped eells was established (Fig. 4). There were alsosmall foei with many osteoclast-like giant eells (Fig. 5), and sm all areas of osteoid and woven bone with a rim of aetivated osteoblasts (Fig. 6). FinaIly, we observed sma11 blood-fi11ed aneurysmal sinusoids, lined by a fibro-histioeytie stroma containing many osteoclast-like giant ee11s (Fig. 7 a, b). Final diagnosis was "solid " variant of aneurysmal bone eyst. Discussion Apparently, "solid" ABC is arare, tumor-like lesion of bone. To our knowledge, only 4 weIl doeumented ca ses
Fig. 2. In MRI, a huge soft tissue mass is seen within the posterior elements of Th 3 and Th 4. In Th 3 th e tumor extends into the spinal canal, compressing the posterior part of the subarachnoidal space.
have been published 24 until today. All patients were children between the ages of 5 and 13, three of them were boys and one a girl. Three lesions were loealized within the spine (Th 2, Th 7 and L 4), one was found in the right ethmoid bone and orbit. Our juvenile patient, a 12year-old girl, also had a spinalIesion at Th 3. The clinical symptoms - pain, loeal swelling, muscle spasm and signs of cord eompression - were similar to those deseribed by Sanerkin and eo-workers 24 in their doeumentation of spinalIesions (cases 3 and 4). Radiographie and MRI findings supported the diagnosis of ABC. In spinal ABCs, almost a11 reeorded lesions originate in the posterior elements of the vertebraeS,20,25,30; oeeasionaIly, a lateral part of one vertebral body isinvolved as weIl5,25,30. Up to 40% of spinal ABCs pass across the intervertebral spaee to another vertebra 10, 11 ,13,30. ABCs are lytie lesions with frequent osseous septa, showing a soft tissue mass surro unded b y athin ossified periosteal shelpo. Most benign tumors and tumor-like lesions of the spine are found exclusively within the posterior elements, without affeetion of the vertebral bod y5, 9,20, 25 . There are, however, two exeeptions: Osteoblastom as may affeet both the posterior
Solid Variant of Aneurysmal Bone eyst . 793
Fig.3. Solid stroma component with fibroblastic and fibrohistiocytic cells arranged in a whorled pattern with scattered mitotic figures suggesting a malignant tumor. HE, x 160.
Fig. 4. Fibromyxoid stroma component with loosely arranged spindie cells. HE, x 160.
arch and the body of the vertebra 19. Giant cell tumors usually originate from the body of the vertebra but can expand to the posterior elements 8,26. On the other hand, most malignant bone tumors are localized within the vertebral body, whereas chordomas may show involvement of both the body and neural arch 21 ,28. Few ABCs show radiographie growth patterns indicating a malignant tumor, such as complete destruction of the cortex, a "moth-eaten" boundary and a huge soft tissue mass 5 . Based on radiographie features alone, the differentiation of spinal ABC from osteoblastoma may be next to impossible, since these may be very similar5,20. Thus, careful histological examination is all the more necessary. In contrast, vertebral osteosarcomas show a predilection for the vertebral body, rarely extending into the posterior vertebral elements5, 11 , 20. Mirra 20 reported six further cases of "solid" ABC in his publication. However, only one of them is radiologically and histologically documented. The patient was a 40year-old woman with a_. lesion in the distal humerus. Radiologically an eccentric destruction of the bone with "blow-out" appearance and sharply circumscribed and
scalloped margins was seen. After reviewing his own collection of six cases Mirra 20 concluded that radiologie features of solid ABC are as variable as those described for conventional ABC. Sanerkin and co-workers 24 as well as Mirra 20 pointed out that, depending on the proliferative component, "solid" ABC may be histologically mi staken for other benign and malignant tumors and tumor-like lesions of bone, among them osteosarcoma and fibrosarcoma, osteoblastoma, giant cell tumor of bone, reparative giant cell granuloma, fibrous dysplasia and ossifying fibroma (osteofibrous dysplasia). In our opinion the lack of anaplasia in all tissue components of the presented case strongly argues against osteo- or fibrosarcoma. Typical, but no atypical mitotic figures were regularly observed in all cases of "solid" ABClO,24. The other entities cited above could be histologically ruled out as follows: Osteoblastoma, a common bone tumor in childhood, which often affects the spine5 ,9, lO, 20,2S, may sometimes show aneurysmal bone cyst-like cavities5,9. The main
794 . G. Edel er al.
Fig. 5. Focus wirh osteoelast-like giant cells resembling a gianr cell tumor. HE, X 160.
Fig. 6. Small areas of interlacing bone trabeculac with an osteoblastic rim in a capillary-rich fibrous stroma containing osteoelasts suspicious of osteoblastoma. HE, X 160.
histological elements of this tumor, however, are numerous interlacing trabeculae or small islands of osteoid bordered by rows of large osteoblasts, a great number of capillaries between the trabeculae and multinucleated giant cells S , 9, 10,20,25. Some of these features were indeed seen in our case, however, only in sm all areas. The predominant tissue component was of the fibroblastic type, which is never present in osteoblastoma 2o . The morphological differential diagnosis between "solid" ABC and giant cell tumor may be extremely difficult, especially when osteoclast-like giant cells are present in areas larger than 1 cm 20 • In our case, however, the foci of osteoclast-like giant cells had a diameter of less than 1 cm. Furthennore, in contrast to ABC, giant cell tumor of the spine almost entirely originates from the body of the vertebra and may secondarily affect the posterior arch 7- 10 ,J8,20,26, as mentioned before. In addition, this tumor hardly ever occurs in patients under the age of 15 5,7, 12, 18,20,23. Giant cell reparative granuloma 2, 3, 15, 17 mayaiso resemble solid areas of ABC and these two lesions may be related 6, 29. But giant cell reparative granuloma is known to
occur only in the skull, jaws, hand, foot and facial bones 2 ,3, 15, 17, 22,27, so this entity can be excluded, too. Fibrous dysplasia, which may sometimes show cystic degenerationS, 20, 25, can also be ruled out in the present case, since this lesion is characterized by a fibrous stroma with short or long curled spicules of wovenbone in bizzare configuration with no osteoblastic rimS,9,1O,20. These features could not be demonstrated in the present tumor. Ossifying fibroma (osteofibrous dysplasia) is also unlikely, occuring almost exclusively in the tibia and occasionally in the homolateral fibula 4,s. Cystic formation is uncommon in this type of lesion. As in case 4 published by Sanerkin and co-workers 24, we failed to detect any foci of degenerated calcifying fibromyxoid tissue with a "chondroid aura" 29, otherwise considered typical for conventional and "solid" ABO, 20, 24. Finally, conventional ABC was also unlikely in our case, because 110 large cyst-like spaces were seen. Nevertheless, we maintail1 the theory that ABC and "solid" ABC are closely related, due to their similarities regarding radiolog-
Solid Variant of Aneurysmal Bone Cyst . 795
Fig. 7. Small blood-filled typical aneurysmal sinusoids (a: HE, (b: HE, X 100).
X
40) lined by fibro-histiocytic cells and many osteoblast-like giant cells
ical features and morphological structures of the cystic walls. The clinical courses of our case and the other published cases were benign 20,24. Local recurrence is possible as with conventional ABC2o. Pathologists should become familiar with the "solid" variant of ABC because of the many possible diagnostic pitfalls which lie in this lesion. i
Acknowledgement Thc authors would like to thank Mrs. E. Griffiths for typing the manuscript.
References 1 Alles JU, Schulz A (1986) Immunocytochemical markers (endothelial and histiocytic) and ultrastructure of primary aneurysmal bone cyst. Hum Pathol 17: 39-45 2 Austin LT, Dahlin DC, Roger RQ (1959) Giant-cell rcparative granuloma and related conditions affecting the jaw-bones. Oral Surg12: 1285-1295
.1 Bhaskar SN, Bernier JL, Godby F (1959) Aneurysmal bone cyst and other giant celilesions of the jaws: Report of 104 cases. J Oral Surg Anesth Hosp D Serv 17: 30-41 4 Campanacci M, Laus M (1981) Osteofibrous dysplasia ofthe tibia and fibula. J Bone Joint Surg 63A: 367-375 5 Camp an ace i M (1990) Bone and Soft Tissue Tumors. Co-authors of soft tissue section: Bertoni F, Bacchini P, Aulo Gaggi Editore Bologna, Springer Verlag, Wien-New York 6 Dahlin DC (1967) Bone Tumors. Ed 2, Charles C Thomas Publ, Springfield, Illinois, USA 7 Dahlin DC, Cupps RE, Johnson EW (1970) Giant-cell tumor: A study of 195 cases. Cancer 25: 1061-1070 8 Dahlin DC (1977) Giant cell tumors of vertebrae above the sacrum. A review of 31 cases. Cancer 39: 1350-1356 9 Dahlin DC, Unni K (1986) Bone Tumors, General Aspects and Data Oll 8, 542 Cases. Ed 4, Charles C Thomas Publ, Springfield, Illinois, USA 10 Dominok GW, Knoch HG (1982) Knochengeschwülste und geschwulstähnliche Knochencrkrankungen. Gustav Fischer Verlag, Stuttgart 11 Erlemann R, Reiser M, Roessner A, Peters PE, Grundmann E (1987) Primäre Knochentumoren und tumorähnliche Läsionen der Wirbelsäule. Eine Analyse radiologischer Dignitätskriterien. RöFo 147: 131-137 12 Goldenberg RR, Campbell q, Bonfiglio M (1970) Giantcell tumor of bone: An analysis of two hundred and eighteen cases. J Bone Joint Surg 52A: 619-663
796 . G. Edel et al. 13 Hay MC, Paterson D, Taylor KF (1978) Aneurysmal bone eysts of the spine. J Bone Joint Surg 60B: 406-411 14 Jaffe HL, Liehtenstein L (1942) Solitary unieameral bone eyst with emphasis on the roentgen pieture, the pathologie appearanee, and the pathogenesis. Areh Surg 44: 1004-1025 15 Jaffe HL (1953) Giant-eell reparative granuloma; traumatie bone eyst, and fibrous (fibro-osseous) dysplasia of jawbones. Oral Surg 6: 159-175 16 Liehtenstein L (1977) Bone Tumors. Ed 5, CV Mosby, Saint Louis 17 Lorenzo JC, Dorfman HD (1980) Giant eell reparative granuloma of short tubular bones of the hands and feet. AmJ Surg Pathol 4: 551-563 18 MeGrath PJ (1972) Giant-eell tumour of bone: An analysis of fifty-two eases. J Bone Joint Surg 54B: 216-229 19 MeLeod RA, Dahlin DC, Beabout JW (1976) The speetrum of osteoblastoma. Am J Roentgenol126: 321-335 20 Mirra JM, in eollaboration with Pieei P, Gold RH (1989) Bone Tumors, Clinieal, Radiologie, and Pathologie Correlations. Vol. 1 and 2, Lea and Febiger, Philadelphia - London 21 Mulder JD, Poppe H, van Ronnen JR (1981) Primäre Knoehengesehwülste. In: Sehinz HR (Ed) Lehrbueh der Röntgendiagnostik, Bd 2/II. Thieme, Stuttgart-New York 22 Ratner V, Dorfman HD (1990) Giant-eell reparative granuloma of the hand and foot bones. Clin Orthop 260: 251-258
23 Sanerkin NG (1980) Malignaney, aggressiveness, and reeurrenee in giant-eell tumor of bone. Caneer 46: 1614-1649 14 Sanerkin NG, Mott MG, Roylanee J (1983) An unusual intraosseous lesion with fibroblastie, osteoclastie, osteoblastie, aneurysmal and fibromyxoid elements. "Solid" variant of aneurysmal bone eyst. Caneer 51: 2278-2286 15 Sehaehowiez F (1981) Tumors and Tumor-like Lesions of Bone and Joints. Springer Verlag, Ncw York-Heidelberg-Berlin 26 Sehwimer SE, Bassett LW, Maneuso AA, Mirra J, Dawson EG (1981) Giant eell tumor of the eervieothoraeie spine. Am J Roentgenol 136: 63-67 17 Sehwinn CP (1976) Differential diagnosis of giant-eell lesions of bone. In: Aekerman LV, Spjut HJ, Abell MR (Eds) Bone and Joints. The Williams and Wilkins Co, pp. 255-258. Baltimore 18 Subbarao K, Jaeobson HG (1979) Primary malignant neoplasms. Semin Roentgenol14: 44-57 19 Tillman BP, Dahlin DC, Lipscomb PR (1968) Aneurysmal bone eyst: An analysis of 95 eases. Maco Clin Proe 43: 478-495 30 Wilner D (1982) Radiology of Bone Tumors and Allied Disorders. Vol. 4, Saunders, Philadelphia
Reeeived June 10, 1991 . Aeeepted in revised form September 19, 1991
Key words: Bone tumors - Aneurysmal bone cyst - Solid variant - Spine tumors G. Edel, M.D., Gerhard-Domagk-Institut für Pathologie, Universität Münster, Domagkstr. 17, D-4400 Münster, FRG
Letters to the Case K. Unni Rochester, USA
The concept of 'solid' aneurysmal bone cyst (ABC) has gained acceptance among pathologists with a special interest in bone tumors since the original description by Sanerkin in 1981. However, this entity is still not widely known in general surgical pathology, orthopedic, and radiology circles. The manuscript by Edel and co-authors appropriately brings attention to this rare, but important entity. Some pathologists object to the term solid aneurysmal bone cyst rightly pointing out that this is an 'oxymoron'. This is true, of course, but the other term proposed for this entity 'giant cell reparative granuloma' is no better because the lesion is certainly not a granuloma. The term proposed by Sanerkin has the advantage of emphasizing the relationship of this lesion to Classic ABC as pointed out by Edel and co-authors. I prefer the designation solid ABC to giant cell
reparative granuloma. A more appropriate term might be giant cell reaction, a term used by Ackerman and Spjut to describe alesion of the sm all bones of the hands and feet, which has also been designated gianr cell granuloma. I agree with the authors that the clinical features and roentgenograms of solid ABC are nonspecific just as they are with more classical ABC. In a small percentage of cases of ABC the roentgenograms look very aggressive and mimic a malignancy. Good radiologists know that they cannot always distinguish ABC from neoplasms, especially telangiectatic osteosarcoma. One of the problems with the diagnosis of solid ABC is that grossly the lesion lacks the typical multicystic appearance that knowledgeable surgeons look for. However, it does not appear fleshy as a sarcoma would, but red and granular such as seen in histiocytosis X.
