Abstract: 【Abstract】 Objective To analyze clinical and pathological features of follicular porokeratosis. Methods Clinical and histopathological data were collected from 8 patients who were diagnosed with follicular porokeratosis in Department of Dermatology, Xijing Hospital, the Fourth Military Medical University from January 2015 to February 2022, and analyzed retrospectively. Results Among the 8 patients, 6 were males and 2 were females. Their average age at onset was 36 years （range, 6 - 67 years）, and the average duration from onset to diagnosis was 6 years （range, 0.5 - 20 years）. No obvious precipitating factors were found. The patients presented with multiple or solitary, small （diameter < 1 cm）, round, long-standing stable reddish-brown maculopapules or plaques with few or no scales on their surface. Most patients had no subjective symptoms, but for some occasional mild itching sensation. Dermoscopic examination of 4 patients showed that keratotic plugs were all present at the opening of hair follicles. Histopathological manifestations of the 8 skin lesions were similar: roughly normal epidermal thickness or mildly irregular acanthosis, parakeratotic columns only at the infundibulum of hair follicles, and thinner or disappeared granular layer containing some dyskeratotic cells. Of the 8 patients, 6 were treated with surgical excision, topical drugs, or laser cautery, etc. The follow-up results showed that surgical excision could cure the primary skin lesions, but could not prevent new skin lesions, and other treatments were basically ineffective. Conclusions Follicular porokeratosis, a special type of porokeratosis, mostly occurs on the facial area of middle-aged males. This disease usually progresses slowly, and is histopathologically characterized by unique parakeratotic columns only present at the opening of hair follicles. The diagnosis of follicular porokeratosis should rely on both clinical manifestations and histopathological findings.

Key words: Porokeratosis, Skin manifestations, Pathologic processes, Dermoscopy, Follicular porokeratosis