History: Lichen spinulosus is a rare, idiopathic, follicular, keratotic dermatosis occurring mostly in children, adolescents and young adults. The male to female ratio is 2:3. No race predilection or seasonal variations have been noted. This condition was first recorded in the literature by Crocker in 1883. He named it “lichen pilaris seu spinulosus.” Since then, there were few case reports until Friedman recorded 35 cases in the Philippines.
Characterized by an acute development of symmetrically distributed follicular, keratotic papules that are sharply grouped in round to oval plaques varying in size from 2 cm to 6 cm, LS can appear on the extensor surfaces of elbows and knees, the neck, buttocks, abdomen and the trochanteric regions. Very rarely, the eruption can be generalized.
A typical LS papule is 1 mm to 3 mm in diameter with skin-colored conical projection and a central 1-mm to 2-mm keratotic spine. The eruption may be asymptomatic or only mildly pruritic. The lesions may spring up simultaneously or in crops.