Surgical Pathology Criteria

Subcutaneous Leiomyosarcoma

Differential Diagnosis

Dermal Leiomyosarcoma Subcutaneous Leiomyosarcoma
90% of lesion must be in dermis >10% must involve subcutaneous tissue
Does not metastasize May metastasize

Malignant Fibrous Histiocytoma Subcutaneous Leiomyosarcoma
Pleomorphic, histologically undifferentiated Elongate or spindled eosinophilic cytoplasm
Typically lacks abundant desmin Typically desmin diffusely positive
  • MFH may be actin positive
  • The distinction between MFH and high grade leiomyosarcoma is not clinically important and may be one of convention
  • Nodular Fasciitis Subcutaneous Leiomyosarcoma
    Indistinct or pale cytoplasm Elongate or spindled eosinophilic cytoplasm
    Torn, tissue paper pattern Fascicular pattern
    Atypical mitotic figures not permitted May have atypical mitotic figures
    Pleomorphism not permitted May be cytologically pleomorphic
    Desmin rare Desmin frequent

    Benign Fibrous Histiocytoma Subcutaneous Leiomyosarcoma
    Frequent foam cells or giant cells Foam cells and giant cells rare
    Typically lacks abundant desmin Typically desmin diffusely positive
    Indistinct cytoplasm Elongate, eosinophilic cytoplasm

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