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 |
