Malignant epithelioid hemangioendothelioma with spindle phenotype: report of an unusual case diagnosed by fine needle aspiration cytology
Epithelioid hemangioendothelioma (EHE) is a rare sarcoma of vascular differentiation that involves various sites and is rarely diagnosed by cytology. A thigh mass in a 36-year-old woman was aspirated. Cytologic examination showed a population of single cells of predominantly spindle morphology. The cells were large, with abundant cytoplasm, and possessed cytoplasmic processes. The nuclei were small and monomorphic and had a single conspicuous nucleolus. A minority of cells had a polygonal shape. Occasionally a perinuclear dense, round cytoplasmic condensation was present in the absence of a clear-cut intracytoplasmic luminae. Necrosis was noted. The tumor expressed vascular markers and was labeled as malignant EHE because of the spindle cell morphology, marked cellularity and presence of necrosis. On cytology, malignant EHE is a very difficult diagnosis to render, especially when the tumor displays spindle cell morphology. In such cases, the differential diagnostic list is that of spindle cell lesions, especially of fibroblastic-myofibroblastic nature. Including endothelial markers in the immunohistochemical panel is crucial to reach the diagnosis. Also, the presence of perinuclear cytoplarmic condensation should be interpreted as evidence of endothelial differentiation on cytology, even in the absence of clearcut intracytoplasmic luminae.