Unilesional Follicular Mycosis Fungoides: Report of 6 Cases and Review of the Literature

Unilesional follicular mycosis fungoides (MF) is a rare variant of cutaneous T-cell lymphoma characterized by selective involvement of the hair follicles by neoplastic T lymphocytes presenting initially as a solitary lesion occupying less than 5% of the body surface; there are 22 previous reported cases. We describe 6 patients with this rare variant of MF, all males (age range 6-64 years; mean age: 28 years) presenting with a solitary lesion primarily on the face and scalp except 1 patient who presented with a truncal lesion. All the patients had the lesions for at least a few months. The lesions were associated with follicular prominence and hair loss. In each, the biopsies showed an atypical folliculotropic lymphocytic infiltrate accompanied by follicular mucinosis in certain cases. The infiltrate involved the lower isthmic part of the follicle, and in 1 case, there was an alopecia areata-like neoplastic lymphomatoid bulbitis. There was no evidence of large cell transformation nor was there a significant degree of infiltration of the interfollicular dermis or epidermis. Higher magnification disclosed marked cerebriform atypia amidst the lymphocytes. Phenotypic studies demonstrated a high CD4 to CD8 ratio in excess of 5 with a significant loss of CD7. One patient developed additional similar lesions involving the thigh and buttock after a period of at least 3-4 years of untreated unilesional MF. Unilesional follicular MF is a potentially curable form of MF with a young male predilection. Early diagnosis and treatment intervention likely define a cornerstone for ensuring the best patient outcome and preventing clinical evolution to either tumor stage MF and or multilesional MF.