Tomoyasu Hattori, Akihiko Uchiyama, Osamu Tago, Yayoi Nagai, Osamu Ishikawa
DOI: 10.2340/00015555-1586

Mycosis fungoides usually follows an indolent clinical course. We report here a rapidly progressive case of mycosis fungoides with peculiar clinical and histological features, presenting as a haematoma-like mass on the thigh accompanied by multiple reddish brown erythematous lesions on the trunk and extremities. Histopathologically, the erythematous lesions showed epidermotropism of atypical T lymphocytes expressing CD4 and prominent syringotropism without syringometaplasia. The haematoma-like lesion consisted of diffuse and dense infiltrates of medium-to-large-sized pleomorphic lymphocytic cells expressing CD30, suggesting that CD30+ large-cell transformation had occurred. Mycosis fungoides presenting as a haematoma-like lesion is rare and may be a poor prognostic sign.