Koebner Phenomenon and Mycosis Fungoides.

Mycosis fungoides (MF) is the most frequent type of primary cutaneous T-cell/NK-cell lymphoma. The Koebner phenomenon is defined as the appearance of cutaneous lesions on previously noninvolved skin following trauma and is observed in a series of cutaneous diseases including psoriasis, lichen planus, viral warts, molluscum contagiosum, etc. In this case report, 3 patients with longstanding MF are presented, the 1st with the appearance of a circumscribed early-stage type MF lesion rapidly following a surgical excision of an infundibular cyst, the 2nd with the appearance of a unique unilateral palmar tumoral MF lesion at the pressure site of a crutch, and the 3rd presented localized MF early stage lesions at the friction site of a belt. This report suggests that some MF patients may experience Koebner phenomenon-induced MF lesions and that MF should be added to the long list of skin diseases potentially exhibiting the Koebner phenomenon.