Acne Keloidalis Nuchae (AKN) is a chronic inflammatory skin disorder that affects the hair follicles primarily located on the posterior scalp and the nape of the neck. The condition’s name is somewhat misleading because it is not a form of common acne, and the resulting lesions are not true keloid scars, though they appear similar. AKN begins as a form of folliculitis that, over time, leads to scarring and permanent changes in the affected skin. This disorder is progressive, meaning it can worsen without appropriate management.
Defining Acne Keloidalis Nuchae
AKN typically first appears on the occipital scalp, which is the lower part of the back of the head, and the posterior neck area along the hairline. The initial manifestation involves small, firm, dome-shaped bumps known as papules, sometimes accompanied by pus-filled lesions called pustules. These bumps are often intensely itchy (pruritus) and can also be painful or tender to the touch.
As the condition progresses, the chronic inflammation causes surrounding tissue to undergo fibrosis, where the small papules begin to coalesce into larger, hardened, raised, and firm plaques. These fibrotic plaques resemble keloids, giving the condition its characteristic appearance. Within these plaques, the hair follicles are permanently damaged and destroyed, resulting in patches of scarring alopecia (permanent hair loss).
In advanced stages, the fibrotic plaques can expand significantly, sometimes forming large, tumor-like masses on the nape of the neck. Secondary bacterial infections are common, which may lead to the development of abscesses and sinus tracts that discharge pus and may be malodorous.
Underlying Causes and Risk Factors
The exact biological cause for the onset of AKN is still not fully understood, but it is fundamentally a disorder of follicular inflammation that leads to scarring. The leading theory suggests that physical irritation or trauma to the hair follicle initiates an inflammatory response, which is then followed by a foreign body reaction to the damaged hair shaft. This process of repeated inflammation and repair leads to the characteristic fibrosis and scarring seen in the condition.
A strong demographic predilection exists, with AKN occurring overwhelmingly in young men of African descent, with a reported male-to-female ratio of up to 20:1. Individuals with tightly curled or coiled hair types are more prone to developing the condition, possibly because the hair shaft re-enters the skin more easily after being cut, triggering an inflammatory reaction similar to ingrown hairs. The incidence rate in this high-risk group ranges from 0.45% to 9.0%.
Chronic irritation is another major contributing factor, often stemming from specific grooming or lifestyle habits. Close shaving or frequent short haircuts that injure the skin or cause irregular shearing of the hair shafts can trigger the initial follicular trauma. Additionally, persistent friction from external sources, such as high shirt collars, tight-fitting hats, or athletic helmets, can exacerbate the condition by continuously irritating the nape of the neck.
While the condition is not caused by poor hygiene, potential genetic predispositions and hormonal influences are also considered likely contributors. Some researchers have suggested that an increased number of mast cells in the occipital region or an increased sensitivity to androgens may play a role in the disorder’s development. The involvement of certain medications, such as cyclosporine or antiepileptic drugs, has also been linked to some cases of AKN.
Medical Management Options
Management of AKN is generally multi-tiered and depends heavily on the severity and stage of the condition. The primary goal is to reduce inflammation, prevent further scarring, and minimize recurrence. Patient education is a foundational step, emphasizing the avoidance of known triggers like close shaves and friction from tight headwear or clothing. Using gentle antimicrobial cleansers containing ingredients like benzoyl peroxide or chlorhexidine can help prevent secondary infection and maintain skin hygiene.
For mild cases characterized by small papules and minimal fibrosis, topical treatments are typically the first line of defense. High-potency topical corticosteroids are used to suppress inflammation, often in combination with topical retinoids, which help to exfoliate the area and soften the hair shafts. Topical antibiotics, such as clindamycin, may be prescribed to address any localized pustules or signs of infection.
Moderate cases, involving larger papules and early plaque formation, often require more aggressive intervention. Intralesional injections of corticosteroids, such as triamcinolone acetonide, are considered a standard of care to reduce the size and firmness of the inflammatory bumps. Oral antibiotics, such as doxycycline or minocycline, are frequently prescribed for several weeks to months to manage extensive folliculitis and control the underlying inflammatory process.
For cases that are severe, extensive, or refractory to medical therapy, advanced procedures are necessary. Laser therapy offers an effective option, with modalities like the 1064-nm Nd:YAG laser targeting the hair follicles to reduce hair burden and subsequent inflammation. Surgical excision is reserved for large, established plaques or tumor-stage lesions that have failed all other treatments, and the resulting wound may be closed immediately or allowed to heal by secondary intention.
Other advanced options include oral isotretinoin, which can be effective in reducing inflammation and sebum production, and cryotherapy, which uses extreme cold to destroy the fibrotic tissue. Radiation therapy is rarely utilized due to the potential risks associated with treating a benign condition, but it may be considered for extremely severe, treatment-resistant cases.