Soft Tissue Myoepithelioma | Dermatopathology

Myoepithelioma of soft tissue.

The findings of a organoid monomorphic glomoid appearing tumor that shows a combined epithelial and smooth muscle phenotypic profile is diagnostic of myoepithelioma of soft tissue. They do exhibit a characteristic cytogenetic profile mainly the EWSR1 gene rearrangement although a variety of different fusion partners such as EWSR1-ZNF444 fusion have been described. There are two broad categories namely benign and malignant variants.

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Slide 1: 54 year-old man with a soft tissue mass.<br><br>The biopsy shows a cellular multinodular tumor.

Slide 2: The tumor is composed of small cohesive nests of glomoid appearing cells.

Slide 3: The cells are very monomorphic and are traversed by delicate capillaries.

Slide 4: They exhibit round to oval nuclei. The cytoplasms demonstrate sharp cytoplasmic membrane. The cytoplasms are abundant and eosinophilic granular in quality. There is no significant mitotic activity or tumor cell necrosis.

Slide 5: SMA immunostain is diffusely positive.

Slide 6: CD138 is also diffusely positive. There was extensive staining of the neoplastic cells for cytokeratin 5/6 and EMA (not shown).