MICHAEL E.MINGMD, MSCE
A punch biopsy specimen of the skin from the left knee showed a dermal neoplasm composed of epithelioid and spindle cells with nuclei containing clumped chromatin and prominent nucleoli set in a homogeneous eosinophilic and basophilic stroma. In some areas, the cells had intracytoplasmic vesicles and/or intracytoplasmic erythrocytes. No necrosis or mitotic activity was identified. The neoplasm was positive for vimentin, CD31, and CD34 and negative for cytokeratin and S100 protein. The histologic findings and the immunophenotype were consistent with an EHE.
Painful Nodule on the Knee—Diagnosis. Arch Dermatol. 2007;143(7):937-942. doi:10.1001/archderm.143.7.937-f