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Soft Tissue Tumors
Malignant fibrous histiocytoma of soft tissue - giant cell type
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)
Revised: 26 June 2009, last major update June 2009
Definition
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● Diagnosis of exclusion - an undifferentiated pleomorphic sarcoma with prominent osteoclast-like giant cells
Terminology
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● Also called malignant giant cell tumor of soft parts, malignant osteoclastoma
Epidemiology
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● Number of cases is declining as specific sarcoma types are identified
● Rare in children
Clinical
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● Extremities and trunk
● Osteoclast-like cells have functional features of osteoclasts (J Pathol 1989;159:53)
Case reports
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● Disseminated tumor (Indian J Pathol Microbiol 2007;50:795)
● 5 year old boy with retroperitoneal tumor (Turk J Pediatr 2007;49:307)
Gross description
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● Hemorrhagic and necrotic
Gross description
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Well circumscribed but
hemorrhagic tumor
Micro description
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● Resembles pleomorphic malignant fibrous histiocytoma, with addition of evenly dispersed osteoclast-like giant cells with 20-100 uniform nuclei that are small and round/oval, accompanied by smaller stromal cells with similar nuclei
● 2-3 MF/10 HPF
● May have angiolymphatic invasion
● Rarely small foci of neoplastic bone or cartilage (some designate these tumors as osteosarcoma or chondrosarcoma)
● No xanthoma cells or siderophages, no necrosis
Micro images
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Osteoclast-like giant cells with uniform nuclei in a pleomorphic MFH
Tumor cells may form neoplastic bone and osteoid Multinucleated giant cells are
strongly positive for acid phosphatase
Cytology description
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● Hypercellular smear composed of cohesive, branching clusters of spindle cells with ovoid, focally hyperchromatic nuclei and inconspicuous nucleoli
● Also interspersed osteoclast-like giant cells, some associated with clusters of spindle cells,
● Hemorrhagic background with cellular debris and occasional spindle cells and lymphocytes (Acta Cytol 2003;47:673)
Cytology images
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Multinucleated osteoclast-like giant cells
Differential Diagnoses
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● Extraskeletal osteosarcoma - has prominent malignant osteoid
● Giant cell tumor of soft tissue - no pleomorphic MFH features
● Leiomyosarcoma - no prominent osteoclastic giant cells, smooth muscle morphology and immunostains
● Melanoma
● Osteoclast-rich carcinoma
● Pleomorphic MFH - no osteoclast-like cells with uniform nuclei
End of Malignant fibrous histiocytoma of soft tissue > giant cell type
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