Abstract

Epithelioid hemangioma (EH) is a benign vascular neoplasm with variable presentation classically identified as a proliferation of well-formed vessels lined by epithelioid endothelial cells bulging into the vessel lumen with abundant eosinophilic cytoplasm and large, rounded nuclei. Worrisome histological features, such as increased cellularity and atypia, are seen in variants of EH despite a benign clinical course. As diagnosis of atypical epithelioid angiomatous neoplasms can be challenging, evolving utilization of immunohistochemical staining has aided in classification. We present a 75-year-old male with history of long-standing vascular papules on the posterior neck which recurred following treatment attempts with conservative excision and laser. Subsequently, the patient had developed numerous satellite lesions with ulceration and elected to undergo complete resection with skin grafting. Histology demonstrated highly cellular sheets of epithelioid cells in a lobular growth pattern with vessels of varying size and morphology. Some vessels displayed a single layer of plump endothelial cells extending into the lumen while others had large, atypical endothelial cells. A dense stroma contained scattered eosinophils. IHC staining of tumor cells was positive for FOSB and negative for AE1/AE3. KI-67 demonstrated a low proliferative index (<10%) and the diagnosis of cellular EH was made. Given its spectrum of presentation, EH may demonstrate banal features or those suggestive of a low-grade malignancy such as epithelioid hemangioendothelioma (EHE). Differentiating atypical EH from EHE can be challenging but identification of FOSB translocations has improved diagnostic accuracy. FOSB demonstrates consistent positivity in cellular EH with negative staining in EHE and epithelioid angiosarcoma. Although negative in classical EH and angiolymphoid hyperplasia with eosinophilia, FOSB positivity in cellular EH with atypical features is a reassuring finding of benignity.

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