Angiolymphoid hyperplasia with eosinophilia affecting the scrotum: a rare case report with molecular evidence of T-cell clonality.

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare, benign entity of unknown pathogenesis. It often presents as painful or pruritic intradermal or subcutaneous red to brown papules or nodules on the head and neck of young adults. A 38-year-old man had a gradually enlarging and mild pruritic plaque on the scrotum for half a year. Pathological findings showed dermal proliferation of anomalous blood vessels lined by plump endothelium with a significant perivascular inflammatory infiltrate composed of lymphocytes, histiocytes, scattered plasma cells and many eosinophils. They were consistent with the diagnosis of ALHE. In addition, the inflammatory infiltrate was analyzed by immunohistochemistry and T-cell receptor (TCR) gene rearrangement. They were mostly CD3(+) T cells and a monoclonal T-cell population. To the best of our knowledge, this is the first case of ALHE affecting the scrotum to be reported in the published work. We present this case to expand the anatomical distribution of this rare tumor. The molecular study of our case supports that ALHE might be a low-grade T-cell lymphoproliferative disorder.