- Email: [email protected]
Primary leiomyosarcoma of bone: Report of two cases in extragnathic bones
Primary Leiomyosarcoma of Bone: Report of Two Cases in Extragnathic Bones Eliane Maria Ingrid Amstalden, MD, PhD, C~lia Savietto Pereira Barbosa, MD, and Reinaldo Gamba, MD, PhD Primary leiomyosarcoma of extragnathic bone is rare; fewer than 50 cases are found in the literature. We report on two patients, adult men, with tumors located on the long bones (close to the knee joint). Radiographically, the tumors were shown as purely destructive, osteolytic, and infiltrative lesions. The diagnosis was based on light microscopy, including i m m u n o h i s t o c h e m i s t r y and ultrastructural examination. The tumor cells were uniformly positive for vimentin and muscle actin, but not for desmin. In one case, the cells were also positive for or-smooth muscle actin. Electron microscopy showed definitive smooth muscle differentiation, including cytoplasmic filaments with focal densities. Both patients died of pulmonary metastases. Ann Diagn Pathol 2: 103-110, 1998. Copyright © 1998 by W.B. Saunders Company Index Words: Bone neoplasm, primary leiomyosarcoma, immunohistochemistry, electron microscopy
p
RIMASRY LEIOMYOSARCOMAS of extragnathic bones are rare. Since the first case described by Evans and Sanerkin i in 1965, not more than 50 cases have been reported in the English-language literature. 1-16Most of them were individual case reports] -3,5,6,811,13and the largest series was published by Berlin et al, 12 including 116 cases of bone leiomyosarcoma from the Swedish Cancer Registry. In Schajowicz's ~7 experience, three of 5,274 bone tumors were classified as leiomyosarcoma. No case was listed by Unni ia from 8,591 primary malignant bone tumors of the Mayo Clinic files. Based on a review byJundt et a116 of 1,240 primary malignant bone tumors, eight cases (0.64%) were diagnosed as leiomyosarcoma. Leiomycsarcoma was introduced into the histological classification of bone tumors by the World Health Organization 19in 1993, and was defined as a spindle-cell malignant neoplasm with smooth muscle differentiation2 ° Its histogenesis remains unclear; early investiga-
From the Department of Pathology, State University of Campinas(UNICAMP), Campinas, SP-Brazil; Department of Pathology and Forensic Medicine,Federal UniversityofMinas Gerais,BeloHorizon& MG-Brazil,"and DepartmentofC~hopedics,State UniversityofCampinas-(UNICAMP), Campincu;SP-Brazil. Address rep~int requests to Eliane Maria Ingrid Amstalden, MD, PhD, Departmentof Pathology,FCM-UNICAMP, CaixaPostal."6111, 13083-970Campinas, SP, Brazil. Copy@t © 1998@ W.B. Saun&rs Company 1092-9134/98/0202/0002$08.00/0
tors proposed that it arose from the vascular smooth muscle of bone marrow vessels, lg However, Sanerkin4 postulated that primary leiomyosarcoma of bone may" also develop from advanced myogenic metaplasia of a sarcoma originating in fibroblastic tissues. The idea that the neoplasm differentiates from pluripotential mesenchymal cells has also been supported by-other workers? ° We report on two cases of primary leiomyosarcoma involving extragnathic bone. The clinical, radiological, and pathological features are presented, including light microscopy by conventional staining, immunohistochemistry, and electron microscopy. Case Reports Case 1
A 29-year-old man presented with a 6-month history of pain in his left knee. At another health care service, 3 months after the onset of symptoms, he was treated by curettage and grafting for a lytic lesion detected in his proximal tibia. When he was admitted to our hospital, radiographic evaluation and computed tomography scans indicated a lytic bone lesion situated anterolaterally in the proximal metaphysis of the left tibia, in the medullary space, measuring approximately 4 cm in diameter. The upper margin was well delimited without marginal sclerosis, but the lower margin was poorly demarcated ("moth-eaten" pattern). Cortical erosion was evident, and there was a soft tissue extension of 2 cm from the
Annals of Diagnostic Pathology, Vol 2, No 2 (April), 1998: pp 103-110
103
104
Amstalden, Barbosa, and Gamba
cortical destruction (Fig 1,A-C). A review of the curettage material yielded the diagnosis of primary leiomyosarcoma of bone. The patient underwent wide resection of the proximal third of the left tibia and received a nonconventional knee prosthesis. At this time there was no evidence of a primary pelvic tumor, nor metastatic disease to lymph nodes or lungs. Fifteen days after surgery an infected subcutaneous hematoma was controlled by drainage and antibiotics. He received no chemotherapy, and l lA years later, died with lung metastasis (Fig 1, D). Case 2
A 22-year-old man sought medical attention for pain, swelling, and difficulty in flexion of his right knee, progressive claudication, and loss of 4 kg in 2 months. Plain x-ray films showed a large osteolytic defect in the distal femur metaphysis extending into the epiphysis, with penetration of cortical bone and soft tissues (Fig 2, A, B). A scintiscan showed that radiotracer accumulation was limited to the site of the lesion, except its central area, suggesting necrosis. A biopsy showed a spindle-cell sarcoma. Amputation above the knee was followed by chemotherapy with bleomycin, actinomycin, and cyclophosphamide alternating with Adriamycin (doxorubicin) and cisplatin. The patient died 6 months later with metastatic disease in the lungs. Material and Methods
Material obtained from biopsies and surgical specimenswas fixed in buffered 10% formaldehyde, part of which was decalcified in 5% nitric acid and embedded in paraffin. Some sections, 4- to 5-/xmthick, were stained with hematoxylin and eosin (H&E), Masson's trichrome, van Gieson's stain, reticulin, phosphotungstic acid-hematoxylin (PTAH), and periodic acid-Schiff(PAS) reaction. For immunohistochemical studies, sections were labeled by the streptavidin-biotin method for demonstration of vimentin, desmin, muscle-specific actin (HHF35), oL-smoothmuscle actin (1A4), S-100 protein, pankeratin (AE1/AE3), CD68 (KP1), and Mac-387 (Dako Corp., Carpinteria, CA). Appropriate positive and negative controls were included with all incubations. Tissue from the two cases was processed in a standard manner for electron microscopy. Results
Pathological findings of the tumors were similar in both cases. Grossly, sections of the surgical specimens showed an extensive, soft, gray-white mass with irregular margins, measuring 9 × 7 × 5.5 cm (case 1) and 10.5 × 8 × 7 cm (case 2). The tumors filled the medullary cavity of the metaphysis, extended through the epiphy-
sis with destruction of the cortical bone, and invaded the neighboring soft tissues. There were areas suggestive of necrosis with cystic degeneration, mainly in case 2 (Fig
2,C). In both cases, light microscopy showed moderately to highly cellular tumors composed of elongated cells arranged in fascicles and interlacing bundles (Fig 3, A, B) with some areas of storiform growth pattern. The cytoplasm was eosinophilic and spindle-shaped, stained red by Masson's trichrome and yellow by the van Gieson method. When PTAH was used, blue fibrillary intracytoplasmic material was occasionally seen. PAS stain showed that some neoplastic cells contained diastase-digestible material mainly in paranuclear areas. Silver impregnation showed a delicate network of reticulin fibers. There was no appreciable increase of collagen fibers. The nuclei of the tumor cells were generally elongated, often cigar-shaped, but sometimes plump and pleomorphic, and contained coarse chromatin (Fig 3, B). Reactive giant cells were observed occasionally in case 1. In both cases, more than 10 mitotic figures per 10 high-power fields (hpf) were found, some atypical (Fig 3, B). Necrotic foci were also present. The results of immunoreactivity tests were strongly positive for vimentin and muscle-specific actin (HHF35) in both cases and for (,-smooth muscle actin (case 1) (Fig 3, C). None reacted to desmin, cytokeratins, S-100 protein, and histiocyte markers (CD68 and Mac-387). Electron microscopy showed the tumor cells were typical of smooth muscle. Most were spindle-shaped, with tortuous indented nuclei. Coarse heterochromatin was found along the inner membrane of the nuclear envelope. The cytoplasm contained mitochondria, free ribosomes, and abundant intermediate filaments (myofilaments) arranged parallel to the nuclei with periodical dense bodies along their course (Fig 4, A, B). Some of these cells also showed subplasmalemmal densities, pinocytotic vesicles, and discontinuous basal lamina. The intercellular stroma consisted of scant collagen bundles. Discussion
Primary leiomyosarcoma of extragnathic bones is rare, with fewer than 50 cases reported in the Englishlanguage literature. 116 Most of the patients are adults, and the disease has a slight predilection for males. ~°,~2 The long bones are the most affected site, mainly at the knee region 12 (as in both cases presented here). Radiological findings indicated an aggressive, but nonspecific, character and consisted ofosteolyticlesions with nonsclerotic, often indistinct, borders situated at the metaphy-
Figure 1. Anteroposterior (A) and lateral (B) radiographs of the left knee. Eccentric osteolytic lesion in the metaphysis of the left tibia with an ill-defined inferior margin without marginal sclerosis, (C) CT section indicates a medullary and cortical bone destruction with tumor extension into soft tissue. (D) Image of metastasis in left lung.
106
Amstalden, Barbosa, and Gamba
Figure 2. Anteroposterior (A) and lateral (B) radiographs of the right distal femur showing an aggressive destructive lesion in the metaphysis extending into the epiphysis. Soft tissue component is seen in panel B. (C) Coronal section through the amputation specimen reveals intramedullary tumor mass with necrotic and hemorrhagic cystic areas destructing the cortical bone and extending into soft tissue.
sis, expanding to the epiphysis and/or diaphysis. In such cases, association with a soft tissue mass at the time of diagnosis is not rare. 1°'12-13 The microscopic appearance of the tumor in the two cases reported here conforms to the pattern seen in
leiomyosarcoma of soft tissues 21 and consisted of broad, interlacing fascicles of spindle cells with eosinophilic cytoplasm, pleomorphic nuclei, mitoses, and necrosis. However, the tumor can still be confused with another spindle-cell mesenchymal neoplasm, such as nonossify-
Primary Leiomyosarcoma of Bone
107
Figure 3. (A) Lamellar bone destroyed by spindle-shaped tumor cells arranged in intersecting bundles. (B) On high power, fascicles of fusiform cells, some plump or pleomorphic, arranged in intersecting bundles. Inset: Atypical mitotic figure. (C) Tumor cells showing cytoplasmic positivity for c~-smooth muscle actin (1A4).
ing fibroma] malignant fibrous histiocytoma,6, ~ malignant spindle-cell sarcoma, 5,9and fibrosarcoma. 4,7Furthermore, that pattern may not be accessible in poorly differentiated cases, and Masson's trichrome and PTAH may fail to show longitudinal intracytoplasmatic fibrils. Immunohistochemical and/or electron-microscopic studies have thus proved helpful in establishing the diagnosis. The mitotic index in leiomyosarcoma of bone can range from 1 to 35 per 10 hpf. 4 Although a number of features such as size, cellularity, atypia, and necrosis correlate to some extent with malignancy, none seems to be so accurate or reproducible in predicting metastasis as mitotic activity. 22 Levels of mitotic activity that seem suitable in evaluating uterine tumors are not valid for soft-tissue tumors. 2I For instance, uterine lesions having between 5 and 9 mitoses per 10 hpf are considered borderline lesions, but in soft tissue, 2I as in bon@ 4 this level of mitotic activity signifies a tumor that is capable of metastasis. Immunohistochemical studies, showing muscle-spe-
cific proteins in the tumor cells, have proved to be a particularly useful diagnostic tool. This finding is possible even in predominantly undifferentiated sarcomas and in formalin-fLxed and decalcified routine material.16 The immunoreactivity for total muscle-specific actin (HHF35) found in our cases has also been observed in all cases of bone leiomyosarcoma byMyers et aP 4 andJundt et al. 16 However, less frequently, these investigators encountered desmin immunoreactivity,14,16, 23 as we observed in our cases, hnmunohistochemical studies for desmin in soft-tissue leiomyosarcomas have produced variable results. 24 Berlin et aP 2 pointed out that the lack of desmin does not exclude a diagnosis of leiomyosarcoma. On the other hand, we found positive ~x-smooth muscle actin in only one of our two cases. Similarly, Young and Freemont 15 found this protein in only one of their four cases of primary leiomyosarcoma of bone. It is possible that our second case might express the unusual variant of smooth muscle actin. 25 However, that was not investigated. Other immunohistochemical studies
108
Amstalden, Barbosa, and Gamba
Figure 4. (A) Ultrastructurally the elongated tumor cells contain abundant thin longitudinal intermediate filaments with periodical condensations. (B) Detail of myofilaments with dense bodies and subplasmalemmal densities.
including S-100 protein, oq-antichymotrypsin, lysozyme, CD68, Mac-387, and epithelial markers have been consistently negative. 15 However, some reactivity for keratin has been observed. 14,16
Electron microscopy showed the tumor cells to be typical of smooth muscle, with myofilaments, dense bodies, and pinocytotic vesicles. Ultrastructural findings may be helpful in cases in which it may not be possible to
Primary Leiomyosarcoma of Bone
demonstrate a-smooth muscle actin or in those submitted to acid decalcification, which may alter antigenicity. The main differential diagnosis of primary leiomyosarcoma of bone includes metastatic leiomyosarcoma, especially in elderly women with a history of uterine lesion or hysterectomy. According to Fechner and Mills, 2° metastases of leiomyosarcoma to bone occur in less than 5% of cases and usually in uncommon sites, distinct from those of primary, bone leiomyosarcoma such as the skull, vertebrae, and scapula. However, for Fornasier and Paley~6the proximal femur metaphysis can be the site of metastatic leiomyosarcoma in 33% of the cases. In the differential diagnosis of spindle-cell, nonmatrix-producing bone tumors the most important is fibrosarcoma, which has clinical and radiographic findings similar to leiomyosarcoma. Morphologically, both are composed of spindle cells in an orderly fascicular pattern. However, in well-differentiated leiomyosarcoma the cells tend to intersect at right angles, and in typical fibrosarcoma they may assume a distinct herringbone pattern. Cytologically, elongation and eosinophilia of the cytoplasmic processes, as well as diffuse and intense positivity for muscle actin and desmin, all favor leiomyosarcoma. Myofibroblastic differentiation may be found in fibrosarcoma, and although this is generally focal, it may still lead to a mistaken diagnosis of leiomyosarcoma. In such cases, ultrastructural studies may be heIpful since myofibroblasts keep the features of a fibroblast with well-developed rough endoplasmic reticulum, interspersed and focally condensed microfilaments, and discontinuous basal lamina? 7 Malignant fibrohistiocytomas (MFH) should also be considered in differential diagnosis. The clinical and radiographic aspects of MFH are similar to leiomyosarcoma. A fascicular or storiform pattern and giant cells can be found in both conditions. In addition, immunohistochemically MFH can show myofibroblastic differentiation and positivity for muscle markers. Fibroblastic osteosarcoma is also another important diagnosis. Increased radiodensity and calcifications point to osteosarcoma. Morphologically, the presence of spindle-ceil areas, giant cells, and presence of osteoid formation asserts the diagnosis of osteosarcoma. Metastatic spindle-cell carcinoma (sarcomatoid carcinoma) may be ruled out by immunohistochemistry. Although positivity for keratin has been described in leiomyosarcomas, 14,16 the reaction involved only filaments CK8 and CK18.16 The biological significance of this finding is unclear. On the other hand, it is not common for carcinomas to express myodifferentiation, and electron microscopy is different in epithelial and spindle muscle cells.
109
The clinical behavior ofprimaIy intraosseous leiomyosarcomas compared to other sarcomas of bone is still uncertain in view of the small number of published cases and because of the lack of uniformity in their management (including radiotherapy, chemotherapy, curettage, resection, and amputation). According to Young and Freemont, 15the risk of early recurrence and metastasis is small if the original tumor is adequately excised at the time of diagnosis. In a review by Myers et al, t4 the mortality in primary bone leiomyosarcoma was 18%, with mean survival of 3.4 years from the time of diagnosis. The lungs were the main site of metastasis and caused death in our two patients. Cutaneous and widespread metastases have also been described by Berlin et al. 12
Acknowledgments We thank L.M. SimSes, T.C. Dunder, and F. Neder for technical assistance, M.A. Gongora for preparing the photographs, and Dr. L.S. Queiroz for helpful discussion of the manuscript.
References 1. Evans DMD, Sanerkin NG: Primary leiomyosarcoma of bone.J Pathol Bacterioi 1965;90:384-350 2. OvergaardJ, Frederiksen P, Helmig O, et ah Primary leiomyosarcoma of bone. Cancer 1977;39:1664-1671 3. Meister P, Konrad E, GokelJM, et ah Case report 59. Skeletal Radiol 1978;2:265-267 4. Sanerkin NG: Primary leiomyosarcoma of the bone and its comparison with fibrosarcoma: A cytological, histologicaI, and ultrastructural study. Cancer 1979;44:1375-1387 5. Wang T, Erlandson RA, Marcove RC, et ah Primary leiomyosarcoma of bone. Arch Pat hol Lab Med 1980; 104:100-104 6. Shamsuddin AK, Reyes F, HarveyJW, et ah Primary, leiomyosarcoma of bone. Hum Pathol 1980; 11:581-583 7. Angewall L, Berlin O, Kindblom L-G, et ah Primary leiomyosarcoma of bone: A study of five cases. Cancer 1980;46:1270-1279 8. Gould VE, Patel iNS, Dardi LE, et ah The quarteriy case: Painful lyLic lesion of the left femur in an adult male. Ultrastruct Pathol 1982;3:301-307 9. Kawai T, Suzuki M, Mukai M, et al: Primary ieiomyosarcoma of bone: An immunohistochemical and uhrastructural study. Arch Pathol Lab Med 1983; 107:433-437 10. Von Hochstetter AR, Eberle lk~D,RuettnerJR: Primary leiomyosarcoma of extragnathic bones: Case reports and review of literature. Cancer 1984;53:2194-2200 11. Eady JL, McKinneyJD. McDonald EC: Primary leiomyosarcoma of bone: A case report and review of the literature.J Bone Joint Surg 1987;69:287-289 12. Berlin O, Angervall L, Kindblom LG, et ah Primary leiomyosarcoma of bone. A clinical, radiographic, pathologic-anatomic, and prognostic study of 16 cases. Skeletal Radiol 1987; 16:364-376 13. Young CL, Wold LE, McLeod RA, et al: Primary leiomyosarcoma of bone. Orthopedics 1988; 11:615-618
110
Amstalden, Barbosa, and Gamba
14. Myers JL, Arocho J, Bernreuter W, et al: Leiomyosarcoma of bone. A clinicopathologic, immunohistochemical, and ultrastructural study of five cases. Cancer 1991;67:1051-1056 15. Young MPA, Freemont AJ: Primary leiomyosarcoma of bone. Histopathology 1991;19:257-262 16. Jundt G, Moll C, Nidecker A, et al: Primary leiomyosarcoma of bone: Report of eight cases. Hum Pathol 1994;25:1205-1212 17. Schajowicz F: Tumors and Tumorlike lesions of Bone, 2nd ed. Berlin, Springer-Verlag, 1994 18. Unni KK: Dahlin's Bone Tumors, 5th ed. Philadelphia, PA, Lippincot t-Raven, 1996 19. Schajowicz F: Histological typing of bone tumors, in World Health Organization International Histological Classification of Tumors, 2nd ed. Berlin, Springer-Verlag, 1993, p 33 20. Fechner RE, Mills SE: Leiomyosarcoma, in Tumors of Bone and Joints. Atlas of Tumor Pathology, Section llI-Fascicle 8. Washington, DC, Armed Forces Institute of Pathology, 1993, pp 205-206
21. Enzinger FM, Weiss SW: Soft Tissue Tumors, 3rd ed. St Louis, MO, Mosby, 1995, pp 491-510 22. Shmookler BM, Lauer DH: Retroperitoneal leiomyosarcoma: A clinicopathologic analysis of 36 cases. AmJ Surg Pathol 1983;7:269-280 23. Takami KM, Ishida T, Ieguchi M, et al: Primary leiomyosm'coma or leiomyoma of the pubic bone? A case report. Int Orthop 1994; 18:248-251 24. Hashimoto H, Daimaru Y, Tsuneyoshi M, et al: Leiomyosarcoma of the external soft tissues: A clinicopathologic, immunohistochemical, and electron microscopic study. Cancer 1986;57:2077-2088 25. Vanderkerckhove J, Weber K: Actin typing on total cellular extracts. A highly sensitive protein-chemical procedure able to distinguish different actins. EurJ Biochem 1981;113:595-603 26. Fornasier VL, Paley D: Leiomyosarcoma in bone. Primary or secondary? Skeletal Radiol 1983;10:147-153 27. Schurch W, Seemayer TA, Lagace R, et al: The intermediate filament cytoskeleton of myofibroblasts: An immunofluorescence and ultrastructural study. Virchows Arch (Pathol Anat) 1984;403:323-336
p
RIMASRY LEIOMYOSARCOMAS of extragnathic bones are rare. Since the first case described by Evans and Sanerkin i in 1965, not more than 50 cases have been reported in the English-language literature. 1-16Most of them were individual case reports] -3,5,6,811,13and the largest series was published by Berlin et al, 12 including 116 cases of bone leiomyosarcoma from the Swedish Cancer Registry. In Schajowicz's ~7 experience, three of 5,274 bone tumors were classified as leiomyosarcoma. No case was listed by Unni ia from 8,591 primary malignant bone tumors of the Mayo Clinic files. Based on a review byJundt et a116 of 1,240 primary malignant bone tumors, eight cases (0.64%) were diagnosed as leiomyosarcoma. Leiomycsarcoma was introduced into the histological classification of bone tumors by the World Health Organization 19in 1993, and was defined as a spindle-cell malignant neoplasm with smooth muscle differentiation2 ° Its histogenesis remains unclear; early investiga-
From the Department of Pathology, State University of Campinas(UNICAMP), Campinas, SP-Brazil; Department of Pathology and Forensic Medicine,Federal UniversityofMinas Gerais,BeloHorizon& MG-Brazil,"and DepartmentofC~hopedics,State UniversityofCampinas-(UNICAMP), Campincu;SP-Brazil. Address rep~int requests to Eliane Maria Ingrid Amstalden, MD, PhD, Departmentof Pathology,FCM-UNICAMP, CaixaPostal."6111, 13083-970Campinas, SP, Brazil. Copy@t © 1998@ W.B. Saun&rs Company 1092-9134/98/0202/0002$08.00/0
tors proposed that it arose from the vascular smooth muscle of bone marrow vessels, lg However, Sanerkin4 postulated that primary leiomyosarcoma of bone may" also develop from advanced myogenic metaplasia of a sarcoma originating in fibroblastic tissues. The idea that the neoplasm differentiates from pluripotential mesenchymal cells has also been supported by-other workers? ° We report on two cases of primary leiomyosarcoma involving extragnathic bone. The clinical, radiological, and pathological features are presented, including light microscopy by conventional staining, immunohistochemistry, and electron microscopy. Case Reports Case 1
A 29-year-old man presented with a 6-month history of pain in his left knee. At another health care service, 3 months after the onset of symptoms, he was treated by curettage and grafting for a lytic lesion detected in his proximal tibia. When he was admitted to our hospital, radiographic evaluation and computed tomography scans indicated a lytic bone lesion situated anterolaterally in the proximal metaphysis of the left tibia, in the medullary space, measuring approximately 4 cm in diameter. The upper margin was well delimited without marginal sclerosis, but the lower margin was poorly demarcated ("moth-eaten" pattern). Cortical erosion was evident, and there was a soft tissue extension of 2 cm from the
Annals of Diagnostic Pathology, Vol 2, No 2 (April), 1998: pp 103-110
103
104
Amstalden, Barbosa, and Gamba
cortical destruction (Fig 1,A-C). A review of the curettage material yielded the diagnosis of primary leiomyosarcoma of bone. The patient underwent wide resection of the proximal third of the left tibia and received a nonconventional knee prosthesis. At this time there was no evidence of a primary pelvic tumor, nor metastatic disease to lymph nodes or lungs. Fifteen days after surgery an infected subcutaneous hematoma was controlled by drainage and antibiotics. He received no chemotherapy, and l lA years later, died with lung metastasis (Fig 1, D). Case 2
A 22-year-old man sought medical attention for pain, swelling, and difficulty in flexion of his right knee, progressive claudication, and loss of 4 kg in 2 months. Plain x-ray films showed a large osteolytic defect in the distal femur metaphysis extending into the epiphysis, with penetration of cortical bone and soft tissues (Fig 2, A, B). A scintiscan showed that radiotracer accumulation was limited to the site of the lesion, except its central area, suggesting necrosis. A biopsy showed a spindle-cell sarcoma. Amputation above the knee was followed by chemotherapy with bleomycin, actinomycin, and cyclophosphamide alternating with Adriamycin (doxorubicin) and cisplatin. The patient died 6 months later with metastatic disease in the lungs. Material and Methods
Material obtained from biopsies and surgical specimenswas fixed in buffered 10% formaldehyde, part of which was decalcified in 5% nitric acid and embedded in paraffin. Some sections, 4- to 5-/xmthick, were stained with hematoxylin and eosin (H&E), Masson's trichrome, van Gieson's stain, reticulin, phosphotungstic acid-hematoxylin (PTAH), and periodic acid-Schiff(PAS) reaction. For immunohistochemical studies, sections were labeled by the streptavidin-biotin method for demonstration of vimentin, desmin, muscle-specific actin (HHF35), oL-smoothmuscle actin (1A4), S-100 protein, pankeratin (AE1/AE3), CD68 (KP1), and Mac-387 (Dako Corp., Carpinteria, CA). Appropriate positive and negative controls were included with all incubations. Tissue from the two cases was processed in a standard manner for electron microscopy. Results
Pathological findings of the tumors were similar in both cases. Grossly, sections of the surgical specimens showed an extensive, soft, gray-white mass with irregular margins, measuring 9 × 7 × 5.5 cm (case 1) and 10.5 × 8 × 7 cm (case 2). The tumors filled the medullary cavity of the metaphysis, extended through the epiphy-
sis with destruction of the cortical bone, and invaded the neighboring soft tissues. There were areas suggestive of necrosis with cystic degeneration, mainly in case 2 (Fig
2,C). In both cases, light microscopy showed moderately to highly cellular tumors composed of elongated cells arranged in fascicles and interlacing bundles (Fig 3, A, B) with some areas of storiform growth pattern. The cytoplasm was eosinophilic and spindle-shaped, stained red by Masson's trichrome and yellow by the van Gieson method. When PTAH was used, blue fibrillary intracytoplasmic material was occasionally seen. PAS stain showed that some neoplastic cells contained diastase-digestible material mainly in paranuclear areas. Silver impregnation showed a delicate network of reticulin fibers. There was no appreciable increase of collagen fibers. The nuclei of the tumor cells were generally elongated, often cigar-shaped, but sometimes plump and pleomorphic, and contained coarse chromatin (Fig 3, B). Reactive giant cells were observed occasionally in case 1. In both cases, more than 10 mitotic figures per 10 high-power fields (hpf) were found, some atypical (Fig 3, B). Necrotic foci were also present. The results of immunoreactivity tests were strongly positive for vimentin and muscle-specific actin (HHF35) in both cases and for (,-smooth muscle actin (case 1) (Fig 3, C). None reacted to desmin, cytokeratins, S-100 protein, and histiocyte markers (CD68 and Mac-387). Electron microscopy showed the tumor cells were typical of smooth muscle. Most were spindle-shaped, with tortuous indented nuclei. Coarse heterochromatin was found along the inner membrane of the nuclear envelope. The cytoplasm contained mitochondria, free ribosomes, and abundant intermediate filaments (myofilaments) arranged parallel to the nuclei with periodical dense bodies along their course (Fig 4, A, B). Some of these cells also showed subplasmalemmal densities, pinocytotic vesicles, and discontinuous basal lamina. The intercellular stroma consisted of scant collagen bundles. Discussion
Primary leiomyosarcoma of extragnathic bones is rare, with fewer than 50 cases reported in the Englishlanguage literature. 116 Most of the patients are adults, and the disease has a slight predilection for males. ~°,~2 The long bones are the most affected site, mainly at the knee region 12 (as in both cases presented here). Radiological findings indicated an aggressive, but nonspecific, character and consisted ofosteolyticlesions with nonsclerotic, often indistinct, borders situated at the metaphy-
Figure 1. Anteroposterior (A) and lateral (B) radiographs of the left knee. Eccentric osteolytic lesion in the metaphysis of the left tibia with an ill-defined inferior margin without marginal sclerosis, (C) CT section indicates a medullary and cortical bone destruction with tumor extension into soft tissue. (D) Image of metastasis in left lung.
106
Amstalden, Barbosa, and Gamba
Figure 2. Anteroposterior (A) and lateral (B) radiographs of the right distal femur showing an aggressive destructive lesion in the metaphysis extending into the epiphysis. Soft tissue component is seen in panel B. (C) Coronal section through the amputation specimen reveals intramedullary tumor mass with necrotic and hemorrhagic cystic areas destructing the cortical bone and extending into soft tissue.
sis, expanding to the epiphysis and/or diaphysis. In such cases, association with a soft tissue mass at the time of diagnosis is not rare. 1°'12-13 The microscopic appearance of the tumor in the two cases reported here conforms to the pattern seen in
leiomyosarcoma of soft tissues 21 and consisted of broad, interlacing fascicles of spindle cells with eosinophilic cytoplasm, pleomorphic nuclei, mitoses, and necrosis. However, the tumor can still be confused with another spindle-cell mesenchymal neoplasm, such as nonossify-
Primary Leiomyosarcoma of Bone
107
Figure 3. (A) Lamellar bone destroyed by spindle-shaped tumor cells arranged in intersecting bundles. (B) On high power, fascicles of fusiform cells, some plump or pleomorphic, arranged in intersecting bundles. Inset: Atypical mitotic figure. (C) Tumor cells showing cytoplasmic positivity for c~-smooth muscle actin (1A4).
ing fibroma] malignant fibrous histiocytoma,6, ~ malignant spindle-cell sarcoma, 5,9and fibrosarcoma. 4,7Furthermore, that pattern may not be accessible in poorly differentiated cases, and Masson's trichrome and PTAH may fail to show longitudinal intracytoplasmatic fibrils. Immunohistochemical and/or electron-microscopic studies have thus proved helpful in establishing the diagnosis. The mitotic index in leiomyosarcoma of bone can range from 1 to 35 per 10 hpf. 4 Although a number of features such as size, cellularity, atypia, and necrosis correlate to some extent with malignancy, none seems to be so accurate or reproducible in predicting metastasis as mitotic activity. 22 Levels of mitotic activity that seem suitable in evaluating uterine tumors are not valid for soft-tissue tumors. 2I For instance, uterine lesions having between 5 and 9 mitoses per 10 hpf are considered borderline lesions, but in soft tissue, 2I as in bon@ 4 this level of mitotic activity signifies a tumor that is capable of metastasis. Immunohistochemical studies, showing muscle-spe-
cific proteins in the tumor cells, have proved to be a particularly useful diagnostic tool. This finding is possible even in predominantly undifferentiated sarcomas and in formalin-fLxed and decalcified routine material.16 The immunoreactivity for total muscle-specific actin (HHF35) found in our cases has also been observed in all cases of bone leiomyosarcoma byMyers et aP 4 andJundt et al. 16 However, less frequently, these investigators encountered desmin immunoreactivity,14,16, 23 as we observed in our cases, hnmunohistochemical studies for desmin in soft-tissue leiomyosarcomas have produced variable results. 24 Berlin et aP 2 pointed out that the lack of desmin does not exclude a diagnosis of leiomyosarcoma. On the other hand, we found positive ~x-smooth muscle actin in only one of our two cases. Similarly, Young and Freemont 15 found this protein in only one of their four cases of primary leiomyosarcoma of bone. It is possible that our second case might express the unusual variant of smooth muscle actin. 25 However, that was not investigated. Other immunohistochemical studies
108
Amstalden, Barbosa, and Gamba
Figure 4. (A) Ultrastructurally the elongated tumor cells contain abundant thin longitudinal intermediate filaments with periodical condensations. (B) Detail of myofilaments with dense bodies and subplasmalemmal densities.
including S-100 protein, oq-antichymotrypsin, lysozyme, CD68, Mac-387, and epithelial markers have been consistently negative. 15 However, some reactivity for keratin has been observed. 14,16
Electron microscopy showed the tumor cells to be typical of smooth muscle, with myofilaments, dense bodies, and pinocytotic vesicles. Ultrastructural findings may be helpful in cases in which it may not be possible to
Primary Leiomyosarcoma of Bone
demonstrate a-smooth muscle actin or in those submitted to acid decalcification, which may alter antigenicity. The main differential diagnosis of primary leiomyosarcoma of bone includes metastatic leiomyosarcoma, especially in elderly women with a history of uterine lesion or hysterectomy. According to Fechner and Mills, 2° metastases of leiomyosarcoma to bone occur in less than 5% of cases and usually in uncommon sites, distinct from those of primary, bone leiomyosarcoma such as the skull, vertebrae, and scapula. However, for Fornasier and Paley~6the proximal femur metaphysis can be the site of metastatic leiomyosarcoma in 33% of the cases. In the differential diagnosis of spindle-cell, nonmatrix-producing bone tumors the most important is fibrosarcoma, which has clinical and radiographic findings similar to leiomyosarcoma. Morphologically, both are composed of spindle cells in an orderly fascicular pattern. However, in well-differentiated leiomyosarcoma the cells tend to intersect at right angles, and in typical fibrosarcoma they may assume a distinct herringbone pattern. Cytologically, elongation and eosinophilia of the cytoplasmic processes, as well as diffuse and intense positivity for muscle actin and desmin, all favor leiomyosarcoma. Myofibroblastic differentiation may be found in fibrosarcoma, and although this is generally focal, it may still lead to a mistaken diagnosis of leiomyosarcoma. In such cases, ultrastructural studies may be heIpful since myofibroblasts keep the features of a fibroblast with well-developed rough endoplasmic reticulum, interspersed and focally condensed microfilaments, and discontinuous basal lamina? 7 Malignant fibrohistiocytomas (MFH) should also be considered in differential diagnosis. The clinical and radiographic aspects of MFH are similar to leiomyosarcoma. A fascicular or storiform pattern and giant cells can be found in both conditions. In addition, immunohistochemically MFH can show myofibroblastic differentiation and positivity for muscle markers. Fibroblastic osteosarcoma is also another important diagnosis. Increased radiodensity and calcifications point to osteosarcoma. Morphologically, the presence of spindle-ceil areas, giant cells, and presence of osteoid formation asserts the diagnosis of osteosarcoma. Metastatic spindle-cell carcinoma (sarcomatoid carcinoma) may be ruled out by immunohistochemistry. Although positivity for keratin has been described in leiomyosarcomas, 14,16 the reaction involved only filaments CK8 and CK18.16 The biological significance of this finding is unclear. On the other hand, it is not common for carcinomas to express myodifferentiation, and electron microscopy is different in epithelial and spindle muscle cells.
109
The clinical behavior ofprimaIy intraosseous leiomyosarcomas compared to other sarcomas of bone is still uncertain in view of the small number of published cases and because of the lack of uniformity in their management (including radiotherapy, chemotherapy, curettage, resection, and amputation). According to Young and Freemont, 15the risk of early recurrence and metastasis is small if the original tumor is adequately excised at the time of diagnosis. In a review by Myers et al, t4 the mortality in primary bone leiomyosarcoma was 18%, with mean survival of 3.4 years from the time of diagnosis. The lungs were the main site of metastasis and caused death in our two patients. Cutaneous and widespread metastases have also been described by Berlin et al. 12
Acknowledgments We thank L.M. SimSes, T.C. Dunder, and F. Neder for technical assistance, M.A. Gongora for preparing the photographs, and Dr. L.S. Queiroz for helpful discussion of the manuscript.
References 1. Evans DMD, Sanerkin NG: Primary leiomyosarcoma of bone.J Pathol Bacterioi 1965;90:384-350 2. OvergaardJ, Frederiksen P, Helmig O, et ah Primary leiomyosarcoma of bone. Cancer 1977;39:1664-1671 3. Meister P, Konrad E, GokelJM, et ah Case report 59. Skeletal Radiol 1978;2:265-267 4. Sanerkin NG: Primary leiomyosarcoma of the bone and its comparison with fibrosarcoma: A cytological, histologicaI, and ultrastructural study. Cancer 1979;44:1375-1387 5. Wang T, Erlandson RA, Marcove RC, et ah Primary leiomyosarcoma of bone. Arch Pat hol Lab Med 1980; 104:100-104 6. Shamsuddin AK, Reyes F, HarveyJW, et ah Primary, leiomyosarcoma of bone. Hum Pathol 1980; 11:581-583 7. Angewall L, Berlin O, Kindblom L-G, et ah Primary leiomyosarcoma of bone: A study of five cases. Cancer 1980;46:1270-1279 8. Gould VE, Patel iNS, Dardi LE, et ah The quarteriy case: Painful lyLic lesion of the left femur in an adult male. Ultrastruct Pathol 1982;3:301-307 9. Kawai T, Suzuki M, Mukai M, et al: Primary ieiomyosarcoma of bone: An immunohistochemical and uhrastructural study. Arch Pathol Lab Med 1983; 107:433-437 10. Von Hochstetter AR, Eberle lk~D,RuettnerJR: Primary leiomyosarcoma of extragnathic bones: Case reports and review of literature. Cancer 1984;53:2194-2200 11. Eady JL, McKinneyJD. McDonald EC: Primary leiomyosarcoma of bone: A case report and review of the literature.J Bone Joint Surg 1987;69:287-289 12. Berlin O, Angervall L, Kindblom LG, et ah Primary leiomyosarcoma of bone. A clinical, radiographic, pathologic-anatomic, and prognostic study of 16 cases. Skeletal Radiol 1987; 16:364-376 13. Young CL, Wold LE, McLeod RA, et al: Primary leiomyosarcoma of bone. Orthopedics 1988; 11:615-618
110
Amstalden, Barbosa, and Gamba
14. Myers JL, Arocho J, Bernreuter W, et al: Leiomyosarcoma of bone. A clinicopathologic, immunohistochemical, and ultrastructural study of five cases. Cancer 1991;67:1051-1056 15. Young MPA, Freemont AJ: Primary leiomyosarcoma of bone. Histopathology 1991;19:257-262 16. Jundt G, Moll C, Nidecker A, et al: Primary leiomyosarcoma of bone: Report of eight cases. Hum Pathol 1994;25:1205-1212 17. Schajowicz F: Tumors and Tumorlike lesions of Bone, 2nd ed. Berlin, Springer-Verlag, 1994 18. Unni KK: Dahlin's Bone Tumors, 5th ed. Philadelphia, PA, Lippincot t-Raven, 1996 19. Schajowicz F: Histological typing of bone tumors, in World Health Organization International Histological Classification of Tumors, 2nd ed. Berlin, Springer-Verlag, 1993, p 33 20. Fechner RE, Mills SE: Leiomyosarcoma, in Tumors of Bone and Joints. Atlas of Tumor Pathology, Section llI-Fascicle 8. Washington, DC, Armed Forces Institute of Pathology, 1993, pp 205-206
21. Enzinger FM, Weiss SW: Soft Tissue Tumors, 3rd ed. St Louis, MO, Mosby, 1995, pp 491-510 22. Shmookler BM, Lauer DH: Retroperitoneal leiomyosarcoma: A clinicopathologic analysis of 36 cases. AmJ Surg Pathol 1983;7:269-280 23. Takami KM, Ishida T, Ieguchi M, et al: Primary leiomyosm'coma or leiomyoma of the pubic bone? A case report. Int Orthop 1994; 18:248-251 24. Hashimoto H, Daimaru Y, Tsuneyoshi M, et al: Leiomyosarcoma of the external soft tissues: A clinicopathologic, immunohistochemical, and electron microscopic study. Cancer 1986;57:2077-2088 25. Vanderkerckhove J, Weber K: Actin typing on total cellular extracts. A highly sensitive protein-chemical procedure able to distinguish different actins. EurJ Biochem 1981;113:595-603 26. Fornasier VL, Paley D: Leiomyosarcoma in bone. Primary or secondary? Skeletal Radiol 1983;10:147-153 27. Schurch W, Seemayer TA, Lagace R, et al: The intermediate filament cytoskeleton of myofibroblasts: An immunofluorescence and ultrastructural study. Virchows Arch (Pathol Anat) 1984;403:323-336