Intravascular papillary endothelial hyperplasia of the neck masquerading as malignancy on fine-needle aspiration cytology

Papillary endothelial hyperplasia (PEH) is an exuberant, usually intravascular endothelial proliferation that, in many respects, mimics angiosarcoma. A case of PEH originally suggestive of embryonal carcinoma by fine-needle aspiration is presented. A 12-year-old boy presented with a palpable mass on the right side of the neck. The mass was subsequently aspirated. Cytopathologic features showed cohesive sheets of polygonal pleomorphic cells with vesicular nuclei and prominent multiple nucleoli in a hemorrhagic background. Cytologic findings were strongly suggestive of metastatic embryonal carcinoma. There was no evidence of a primary lesion. After the mass was surgically excised, the pathologic findings showed PEH. A retrospective immunocytochemical stain for factor VIII-related antigen on a destained ethanol-fixed smear confirmed the endothelial nature of the polygonal cells. A vascular lesion should be considered, especially when atypical polygonal cells in a hemorrhagic background are present, as they were in this case.