Acne keloidalis nuchae (AKN), or folliculitis keloidalis, is a chronic inflammatory disease in which pustules and keloid-like papules and plaques occur at the nape of the neck, occipital scalp, and sometimes extend up to the vertex scalp. Despite its name, it is generally accepted that the lesion is not associated with acne, is not a true keloid, and can occur beyond the nuchal area.

The presence of keloids at other locations or having a family history of keloids are not features of the disease. The overwhelming majority of patients with AKN are young Black men. AKN has been reported in other racial and ethnic groups, including individuals of Hispanic and Korean descent and White people. Women are rarely affected unless they shave their hair at the nape of the neck. AKN is rare in patients before puberty or after age 50.

The condition is often painful and disfiguring. Inflammation of the hair follicle and fibrosis of the tissue typically result in scarring, including scarring alopecia. The etiology is unclear; many different hypotheses and factors have been proposed. Inflammation is key in the pathogenesis of AKN; however, whether inflammation is a primary or secondary phenomenon is unclear. Earlier literature suggests that AKN was a form of mechanically induced folliculitis, and it is known that AKN is associated with localized mechanical irritation from shirt collars, football or military helmets, or trauma from shaving or haircuts. Despite this association, AKN has been classified as a primary form of inflammatory scarring alopecia.

The strong male predilection suggests that androgens play a role in pathogenesis. It has been discussed in the literature that the kinky, curly nature of Black hair and the tendency of this curvature to lead to penetration of the skin and development of ingrown hairs (which is known to be pathogenic in pseudofolliculitis barbae) could play a role in the pathogenesis. However, histology and dermoscopy have not demonstrated ingrown hairs to be a feature of AKN. There is also no reported association between the occurrence of pseudofolliculitis barbae and AKN.

Another proposed mechanism is aberrant immune reaction to various antigens including cosmetic products, sebum, Demodex, bacterial skin flora, or dermatophytes. One study showed a higher incidence of seborrheic dermatitis in patients with AKN, raising the question of whether dermatophytes could play a role in pathogenesis.

Other factors that have been suggested are obesity and metabolic syndrome, and certain medications.