Acne necrotica, also known as necrotizing lymphocytic folliculitis and folliculitis necrotica, is a rare disorder with a chronic relapsing course characterized by follicular papules and pustules, predominantly affecting the anterior hairline and scalp. It is typically seen between age 30 and 50, with most recent sources reporting a female predilection. The etiology of acne necrotica is unknown, although Staphylococcus aureus and Corynebacterium acnes have been isolated from the pustules. Despite its name, it is not a variant of acne.
The acne necrotica varioliformis variant is characterized by evolution of the papules and pustules to form depressed scars resembling those seen in smallpox (varioliform). These lesions may be painful with little to no pruritus. The acne necrotica miliaria variant is characterized by small vesicopustules that form superficial crusts and erosions without scarring. These lesions tend to be very pruritic.