Retiform hemangioendothelioma: presentation of a case expressing D2-40.

Retiform hemangioendothelioma (RH) is a low-grade angiosarcoma with low metastatic risk, usually occurring as a single lesion on the trunk or extremity in middle-aged adults. Histopathology shows a distinctive pattern with arborizing blood vessels arranged in a retiform pattern (similar to rete testis tissue) and focal papillae with fibrosclerotic (hyaline) cores. The blood vessels are lined by comparatively monomorphic endothelial cells, frequently presenting a hobnail pattern. We report a case of RH presenting as an indolent brownish plaque on the back of a 17-year-old male. Surgical resection and sentinel lymph node biopsy showed no evidence of metastasis. In contrast to the recent literature, this case of RH showed positivity for D2-40, a marker of lymphatic endothelium. We also report ultrastructural findings for this case of RH.