Abstract: The skin lesions of folliculotropic mycosis fungoides (FMF) are diverse and prone to misdiagnosis in the early stages, while the prognosis of late stage patients is generally poor. Timely pathological biopsy and early diagnosis are extremely important. This article retrospectively analyzes the clinical and pathological data of four patients with FMF in our hospital from August 2022 to February 2024. Among them, 3 cases were male and 1 case was female. The average age of onset was 51.5 years and average age of diagnosis was 54.25 years. The skin lesions of the two patients originated from the face, mainly manifested as follicular papules, which were misdiagnosed as benign acantholytic skin disease and eosinophilic dermatosis respectively. The other 2 cases originated from the trunk and limbs, mainly plaques and nodules, and were misdiagnosed as drug eruption, connective tissue disease, eczema, and psoriasis, respectively. The main pathological manifestation is infiltration of lymphoid cells around hair follicles, with some nuclei being large and deeply stained. Immunohistochemistry showed CD3 (+), CD4 (+), CD5 (+), CD8 partially or slightly (+); CD30、CD20 and CD79a slightly scattered positive or negative. The main treatments of the 4 patients were acitretin capsules, human interferon injection, and UVB/UVA phototherapy and superficial X-ray irradiation therapy at the local plaque. The follow-up period was from 3 months to 2 years, 3 patients had good compliance, and continued to take acitretin capsules and inject human interferon, and their condition improved, the other patient changed to traditional Chinese medicine treatment himself, then the condition worsened.

Key words: folliculotropic mycosis fungoides, clinical pathology, prognosis