Keratosis Follicularis Squamosa in Unilateral Buttock: A Case Report and Literature Review in China

This case report describes a 21-year-old man with keratosis follicularis squamosa (KFS) presenting uniquely with unilateral distribution on the left buttock, a potential new clinical subtype. KFS is typically characterized by symmetrical scaly patches and keratinization disorders, primarily reported in Japan and China. The patient's lesions resolved completely after two months of treatment with asiaticoside ointment, with no recurrence after 2 years. The report reviews 9 other cases in China, highlighting the disease's prevalence in adolescents and young adults, and discusses potential contributing factors such as bacterial infection and genetic predisposition. The findings suggest that unilateral KFS could be a distinct clinical subtype, expanding the understanding of the disease's manifestations.