Tinea cruris, also called spiny follicular keratosis or tinea cruris, is characterized by small follicular papules topped with fine, filamentous keratinous spicules, and is most common on the nape of the neck in children. The cause of the disease is not clear. Some scholars believe that it is related to vitamin A deficiency, while others believe that it may be a reaction of the body to infections, medications, or immunity. Other scholars believe that there are cases of dominant inheritance in the family, which may be a subtype of trichotillomania. The clinical manifestation is a small follicular papule the size of a pinhead with a small filamentous keratinous spine in the center, which is firm to the touch. Treatment can be internal vitamin A, vitamin E or topical vitamin A ointment, urea ointment, the general prognosis of the chronic course is relatively good.