Surgical Pathology Criteria

Sclerosing Epithelioid Fibrosarcoma

Differential Diagnosis

MUC4 reactivity (strong, diffuse) appears to be sensitive and specific for low grade fibromyxoid sarcoma (100%) and the related sclerosing epithelioid fibrosarcoma (78%) with reactivity in mesenchymal lesions seen othewise only in synovial sarcomas (weak focal reactions may be seen in other lesions) (Doyle 2011, 2012)

Low Grade Fibromyxoid Sarcoma Sclerosing Epithelioid Fibrosarcoma
Alternating fibrous and myxoid areas Generally myxoid stroma
Spindled or stellate cells Round, oval or angulated cells
EMA occasionally weak or focal EMA positive in 50% of cases
Quite different in appearance but based on cases with shared t(7;16) and cases with shared histologic features it has been suggested that these represent ends of a common spectrum

 

Carcinoma Sclerosing Epithelioid Fibrosarcoma
Usually widespread strong keratin staining Infrequent keratin staining, usually focal and weak
History of carcinoma primary No known primary
EMA may be positive in sclerosing epithelioid fibrosarcoma

 

Mesenchymal Chondrosarcoma Sclerosing Epithelioid Fibrosarcoma
Myxoid stroma Sclerotic, hyalinized stroma
Eosinophilic cytoplasm stretched between cells Cytoplasm usually clear, not stretched between cells
Both may grow in lobules with cords of cells

 

Adult Fibrosarcoma Sclerosing Epithelioid Fibrosarcoma
Spindled cells Round, oval or angulated cells
Scant stroma Prominent hyalinized stroma
EMA negative EMA focal weak positive in 50%
Sheets of cells Cords and nests of cells
Some tumors have areas of both patterns

 

Monoophasic Synovial Sarcoma Sclerosing Epithelioid Fibrosarcoma
Ropy collagen often surrounding cellular nests of sarcoma Hyalinized background
Sheets and nests of cells Cords and nests of cells
Keratin 50-80% positive Keratin rare, focal and weak
t(X;18) essentially all cases No t(X;18)
Both may be EMA positive

 

Ossifying Fibromyxoid Tumor Sclerosing Epithelioid Fibrosarcoma
EMA negative EMA 50% positive
Peripheral rim of bone in most cases Focal metaplastic bone at most

 

Osteosarcoma Sclerosing Epithelioid Fibrosarcoma
EMA negative May be EMA positive
Osteoid formed by malignant cells Sclerotic, hyalinized stroma; bone formation if present is metaplastic

 

Clear Cell Sarcoma Sclerosing Epithelioid Fibrosarcoma
S100 and HMB45 70-90% positive EMA 50% positive, HMB45 negative
Fibrous septa around nests of cells Cords and nests of cells in prominently sclerotic and hyalinized stroma
Both may have clear cytoplasm

 

Epithelioid Sarcoma Sclerosing Epithelioid Fibrosarcoma
EMA and keratin often strongly positive EMA and keratin negative or focal and weak
Often granuloma-like Cords of cells in hyalinized stroma
Eosinophilic cytoplasm Clear cytoplasm

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