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Soft Tissue Tumors
Malignant Fibrous Histiocytoma (MFH) of soft tissue - pleomorphic
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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● Pleomorphic sarcoma composed of fibroblasts, myofibroblasts and histiocyte-like cells
● Diagnosis of exclusion; must sample generously and search for other components to rule out a dedifferentiated tumor or evidence of specific differentiation other than fibroblasts or myofibroblasts
Terminology
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● Also called undifferentiated pleomorphic sarcoma
● See also Bone, Eye-conjunctiva and Heart-tumor chapters
● First described in 1964 (Cancer 1964;17:1445)
● Pleomorphic: variation in cytoplasmic and nuclear size throughout the tumor, not just “funny looking cells”
Epidemiology
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● Historically considered the most common adult soft tissue sarcoma
● Usually age 50+ years in extremities or retroperitoneum, large and deep-seated with progressive enlargement
● Sarcomas adjacent to orthopedic implants or post-radiation are usually osteosarcoma or MFH (Mod Path 2001;14:969)
Xray images
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Tumor surrounds intramedullary nail
Treatment and prognosis
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● Wide local excision is occasionally curative in extremities; adjuvant or neoadjuvant radiation and chemotherapy often used
● Recurs locally, may metastasize to lungs or regional lymph nodes
● Almost never presents as metastasis with unknown small primary
● 5 year survival is 50-60% for all high grade pleomorphic sarcomas, better for some subtypes (dedifferentiated liposarcoma)
● Call “borderline” if features are between fibrous histiocytoma and MFH, and treat with wide local excision
● Good prognostic factors: superficial, small size, low grade
● When occurs in skin, is difficult to differentiate from atypical fibroxanthoma or DFSP
Gross description
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● Large, may appear circumscribed (but is not); subcutaneous lesions are usually 5 cm or less, retroperitoneal lesions may be 20 cm
● Cut surface is fibrous or fleshy with hemorrhage, necrosis or myxoid change
Gross images
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Implant related MFH is tan, Buttock tumor Buttock tumor
fleshy and surrounds femur
Cystic change and necrosis
Micro description
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● Variable cellularity, storiform pattern (cells emanate from a central focus)
● Tumor cells are very pleomorphic and bizarre with foamy cytoplasm and marked atypia, in a background of inflamed collagenous stroma
● May represent end stage of various sarcomas with common morphologic features of pleomorphism and storiform growth pattern
● Numerous mitotic figures, including atypical forms
● Rarely metaplastic (not neoplastic) bone or cartilage
Micro images
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Striking low power appearance Characteristic giant cells Mixture of fibroblasts
due to cellularity, whorled pattern, with bizarre nuclei and histiocyte-like cells
marked pleomorphism with including multinucleated
bizarre nuclei forms
Vague storiform pattern is Tumor cells have abundant Strap like cells resemble
often present, at least eosinophilic cytoplasm and rhabdomyoblasts
focally bizarre nuclei, and resemble
a muscle tumor
Features of a pleomorphic Numerous mitotic figures, Frequent tumor cell
sarcoma without specific some bizarre forms necrosis, not seen in
differentiation benign fibrous
histiocytoma
Storiform pattern Post-implant tumor shows whorling
Other images: features of a pleomorphic sarcoma without specific differentiation
Cytology description
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● Single cells to large storiform fragments
● Cells are spindled, plasmacytoid and pleomorphic (often multinucleated), all with malignant nuclear morphology (Cancer 1997;81:228)
Cytology images
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Storiform pattern Storiform pattern Large pleomorphic tumor
cell with phagocytosis of
neutrophils
Marked anisonucleosis and Large cells with pleomorphic nuclei
irregularity of nuclear membranes and bizarre mitotic figures
Positive stains
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● Positive, but not useful for diagnosis: vimentin, alpha-1-antitrypsin, alpha-1-antichymotrypsin, Factor XIIIa, CD68 (may be due to lysosomal granules in non-histiocytic cells); also CD10, CD34, CD99 (35%, J Cutan Pathol 2006;33:24)
Negative stains
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● Keratin (usually), melanocytic markers, CD45, S100, muscle markers
Electron microscopy
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● No features of a specific lineage
● Relatively undifferentiated fibroblastic, myofibroblastic or primitive mesenchymal cells, some with phagocytic properties
Electron microscopy images
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Tumor cell has fibroblastic features
Molecular / cytogenetics
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● Highly complex karyotype, usually triploid or tetraploid
● Gene expression profiles may be somewhat similar to other sarcomas (Mod Path 2007;20:749, but see Langenbecks Arch Surg 2009 Jan 22 [Epub ahead of print])
Differential Diagnoses
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● Myxofibrosarcoma - 10%+ myxoid foci
● MFH-giant cell - if numerous osteoclast-like giant cells
● MFH-inflammatory - if marked inflammatory cells
● Other sarcomas - if evidence of specific differentiation, particularly pleomorphic leiomyosarcoma, rhabdomyosarcoma and liposarcoma
● Atypical fibroxanthoma - cutaneous, small and superficial
● Leiomyosarcoma - smooth muscle differentiation
● Histioid leprosy
● Metastatic renal cell carcinoma - keratin+
End of Malignant Fibrous Histiocytoma of soft tissue > pleomorphic
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