Abstract: 【Abstract】 Objective To analyze clinical and pathological characteristics of 9 cases of hypopigmented mycosis fungoides （HMF）. Methods Nine patients with clinically and histopathologically confirmed HMF were collected at Department of Dermatology, Hangzhou Third People's Hospital from 2014 to 2018, and their clinical and pathological manifestations and follow-up findings were retrospectively analyzed. Results Among the 9 patients, there were 7 males and 2 females; the age ranged from 6 to 29 years （average, 12.4 years）; the duration of disease varied from 6 months to 3 years （average, 20.7 months）. All skin lesions manifested as poorly demarcated, irregular, hypopigmented patches, some hypopigmented patches were confluent, and hypopigmented patches were covered with scales in 2 cases. Wood′s lamp examination of hypopigmented patches showed a grayish-white color with weak fluorescence. Dermoscopic images showed white scales on the lesions and blood vessels distributed in spermatozoa-like, punctiform or short linear patterns. Reflectance confocal microscopy showed mild hypopigmentation in the basal layer without obvious depigmentation, and highly-refractive atypical cells at the dermo-epidermal junction. Histopathological examination of the 9 cases showed epidermotropic phenomenon of atypical lymphocytes, and some cells clustered and formed Pautrier′s microabscess, immunohistochemical staining revealed that all the cells expressed T cell phenotypes, and were mainly infiltrating CD8+ T cells. The 9 patients were treated with narrow-band ultraviolet B （NB-UVB）, and all of them achieved clinical complete response. During a follow-up of 23.8 months on average, 2 patients experienced recurrence, and they achieved clinical complete response again after NB-UVB treatment. Conclusions HMF progresses slowly, and NB-UVB treatment is effective. There is the possibility of recurrence after clinical recovery in patients with HMF, and a long-term follow-up is needed.

Key words: Mycosis fungoides, Hypopigmentation, Skin manifestations, Pathologic processes, Ultraviolet therapy, Treatment outcome