Acne Keloidalis Nuchae (AKN) is a chronic inflammatory skin lesion that was first defined by Kaposi in 1869. Inflammation of the hair follicles causes the development of keloid-like papules and pustules at the back of the neck and scalp. This condition, known as AKN, initially develops as acne-like breakouts with marked erythema, which later turns into fibrotic plaques and scarring alopecia on affected skin lesions. The incidence of AKN is reported between 0.45% and 9%. AKN mostly develops between the ages of 18 and 25 years. It is usually found in African men, but cases are also reported in Hispanic and Asian populations.¹
AKN is a chronic form of folliculitis and peri-folliculitis, initially presenting as mild papules and pustules on the back of the neck that can progress to inflamed plaques. These plaques grow with time and coalesce to form large painful nodules with hypertrophic scarring, which has a disfiguring appearance. The lesion is prone to secondary infection with bacterial manifestations, causing abscess formation and purulent discharge. However, AKN is a misnomer as these lesions do not occur due to acne vulgaris and are not likely keloids histologically.²

Symptoms of Acne Keloidalis Nuchae

Acne Keloidalis Nuchae presents with a sequence of clinical findings, often ranging from mild rashes initially to developing into thick pustules with complaints of bleeding, hair loss, and scarring as the condition worsens. The sequence is usually as follows:

AKN is initially presented as a rash at the posterior part of the neck or the back of the scalp.

These rashes are initially itchy and later turn into papules and pustules. A papule is a small inflammatory bump on the skin surface, whereas pustules are skin elevations consisting of purulent discharge.
In active lesions, pain and contact bleeding are common features.
These lesions can combine to form a horizontal band or irregular plaques at the back of the scalp in the form of a raised scar, which can lead to alopecia.
Near the edge of the scar, ingrown hair and tufted hair can develop. Tufted hair is presented as multiple hair shafts outgrown from a single hair follicle.³

Etiology

Chronic inflammation in the hair follicles at the back of the scalp causes AKN. The potential factors that can lead to AKN are:

Tight headgear and shirt collars cause continuous friction and irritation, especially in hot and humid weather.
Skin injury caused by frequent shaving and trimming with unhygienic tools can cause ingrown hair due to inflammation of hair follicles.
Genetic predisposition with curly and coarse hair since it is mostly common in African males.
Certain medications like immunosuppressants and antiepileptic drugs like carbamazepine.
Chronic low-grade bacterial infections.
Obesity causes neck folds posteriorly, resulting in friction and unnecessary skin rubbing.
Immune-compromised diseases like cancer and AIDS.

AKN can be associated with other diseases like metabolic syndrome, as stated in the literature.⁴ The individuals with metabolic syndrome have diabetes, obesity, dyslipidemia, and hypertension, which causes the weakening of the follicular wall and dysfunctioning of the sebaceous glands, leading to the release of antigens that exacerbate the process of inflammation.

Diagnosis of Acne Keloidalis Nuchae

The diagnosis of AKN begins with a history of acne-like breakouts with itchiness present at the nape of the neck. These lesions grow in number and size with time, along with their discomfort. Dermatologists diagnose AKN clinically by looking for signs like papules, pustules, scarring with hair loss, hair tufting, and infection.
In advanced cases, the lesion appears to be a painful large elevation on the occipital region with scarring and alopecia.⁵
If needed, a biopsy reveals inflammatory cells, dermal scarring, and follicle disruption. Microscopic examination shows sebaceous gland destruction, inflamed follicles, and thinning epithelium with multiple hairs sharing a similar structure. Connective tissue replaces hair follicles.

Differential Diagnosis

Some of the most common differential diagnoses for acne keloidalis nuchae include:

Acne Conglobata

It is a chronic inflammatory autoimmune disease that manifests as painful, pus-filled comedones and abscesses on the face, neck, chest, arms, buttocks, and thighs.
Clogged pores develop deep-seated nodules with a cyst-like appearance.⁶

Acne Vulgaris

Acne, commonly known as pimples, spots, or zits, typically appears on the face.
It presents as both inflammatory and non-inflammatory skin lesions, including papules, pustules, and comedones (whiteheads & blackheads). Unlike AKN, acne does not cause hypertrophic scarring.⁷

Hidradenitis Suppurativa

Acne inversus, characterized by painful lumps under the skin, can significantly hinder daily activities. It usually develops in areas where skin rubs together, such as armpits, groin regions, buttocks, and breasts.
This condition primarily affects females and develops after puberty, typically before age 40, distinguishing it from AKN. It may appear as blackheads or painful small lumps that progress to larger lumps with tunnel formation underneath that drain foul-smelling pus and sometimes blood.

Folliculitis Decalvans

It is a chronic inflammatory skin disease commonly caused by an abnormal immune response to the bacteria Staphylococcus aureus. In contrast to AKN, which primarily affects the back of the neck and forms keloid-like scars, this condition can affect hair-bearing areas of the body, often including the arms, face, and scalp.
Doctors diagnose the skin infection by clinical examination, or swabs of the infected area to test for bacteria and fungus. Clinically presented as irregular, atrophic white patches of scarring and hair loss. Hair tufting is present, multiple hair shafts emerge from the single hair follicle.
Peri-follicular erythema, crust, erosions, and pustules can be seen through dermoscopy.⁸ The complication of folliculitis can lead to progressive hair loss and even squamous cell carcinoma.

Management & Treatment of Acne Keloidalis Nuchae

A dermatologist considers how the skin appears and the pain level before any treatment planning, including:⁹

Patient Education to Prevent Disease Progression

The etiological factor of AKN, which causes continuous skin irritation, is a major focus in understanding the progression of the lesion. The dermatologist will work with you to identify the causes, such as wearing tight clothes, friction with shirt collars and headgear, frequent closed shaves, and haircuts from outside with unclean instruments.

Use of Anti-Inflammatory & Antimicrobial Shampoo

As skin with lesions is more prone to infection, antimicrobial cleansers and shampoos containing benzoyl peroxide are prescribed to prevent secondary infection development and reduce inflammation.

Retinoid

Alpha hydroxyl acid or retinoid is prescribed to soften coarse hair and unclog hair follicles.

Topical Steroids

Doctors use corticosteroids to treat AKN, applying them topically to skin lesions with scars and bumps to reduce inflammation. For advanced cases, intralesional steroid injections may be necessary.

Antibiotics

Doctors sometimes prescribe antibiotic pills or topical creams to treat infections by applying them to the skin lesion area.

Surgical Drainage of Abscess

If AKN persists for some time, there’s an increased risk of developing a secondary infection. This infection can lead to the formation of pus-filled abscesses. In some cases, these abscesses can form a sinus tract under the skin, which can be painful for the patient. In such cases, dermatologists will recommend surgical drainage of the abscess and prescribe medication to treat the infection.

Surgical Excision of Lesion

If the above-mentioned treatments don’t manage the skin lesion, your dermatologist may recommend surgically excising the keloid-like scar. In surgical excision, the surgeon removes the scar with a surgical blade and leaves the wound to heal by secondary intention, which takes 6-8 weeks to heal for wound closure.

Electro Surgery

High-frequency electrical currents excise the lesion and coagulate small blood vessels. Non-invasive treatment options include:

Laser Therapy:

Laser therapy is performed by trained medical professionals and dermatologists. 6-8 sessions are required for optimal results. Laser therapy is a non-invasive, effective treatment option available for AKN. The laser options to treat keloid-like scarring in AKN are:

Pulsed Dye Laser (PDL): This laser targets the blood vessels in the lesion, minimizing the inflammation associated with AKN.
CO2 Laser: Works on deep lesions with scar revision and boosting collagen production for scar healing.
Nd: YAG Laser: This laser is found to be potentially effective for the early and late phases of AKN. It targets deep skin layers, collagen production, and the reduction of inflammation.

Low-Dose Radiation Therapy (LDRT)

Dermatologists recommend LDRT for various skin lesions, including AKN. A practitioner applies a controlled dose of radiation to the skin affected by the lesion. The radiation helps reduce inflammation, minimizing the number and size of papules. It reduces hair growth, leading to scar tissue shrinkage and inhibiting the formation of scar tissue in AKN. Sometimes, radiation therapy may cause potential side effects like dryness, redness, and skin irritation after a session.

Maintenance Therapy in Acne Keloidalis Nuchae

AKN treatment can achieve recovery through the use of maintenance therapy.

Washing the back of the neck with a gentle cleanser containing the antimicrobial element benzoyl peroxide and the anti-inflammatory salicylic acid helps reduce the inflammation and build-up of dead cells that clog the hair follicles.
Apply dermatologist-prescribed medication on the lesion site.
Avoid self-inflicted injury to the lesion site that can cause AKN to recur.
Sharp, unclean blades can irritate and traumatize your skin. Use electric razors.
Apply sunscreen to protect from sun rays, which cause sunburn and hyperpigmentation on the lesion site.

Conclusion

AKN is a difficult skin condition that causes painful papules and scarring at the back of the neck. It requires comprehensive management of symptoms.
Doctors use medication as the first-line treatment for mild AKN, and they may consider surgical excision for visible skin scars and fibrosis.
The management of AKN with noninvasive options like laser and light therapy is efficient, with an 89-92% improvement in lesion texture and inflammation. Self-care for prevention from AKN plays an important role, like gentle cleansing, sun protection, and avoiding trauma to the lesion site.

Refrences

1
Miteva, M., & Sabiq, S. (2021). Acne keloidalis nuchae. In Hair Disorders (pp. 117-120). CRC Press.
2
Umar, S., Lee, D. J., & Lullo, J. J. (2021). A retrospective cohort study and clinical classification system of acne keloidalis nuchae. The Journal of Clinical and Aesthetic Dermatology, 14(4), E61.
3
Ogunbiyi, A. (2016). Acne keloidalis nuchae: prevalence, impact, and management challenges. Clinical, Cosmetic and Investigational Dermatology, 483-489.
4
Kridin, K., Solomon, A., Tzur-Bitan, D., Damiani, G., Comaneshter, D., & Cohen, A. D. (2020). Acne keloidalis nuchae and the metabolic syndrome: a population-based study. American Journal of Clinical Dermatology, 21, 733-739.
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Labib, A., Salfity, L., & Powell, B. (2021). Acne keloidalis nuchae: a staged reconstruction. Cureus, 13(9).
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Canpolat, F., Kurmuş, G. I., & Gönül, M. (2017). ACNE CONGLOBTA. Romanian Journal of Clinical and Experimental Dermatology, 4(2).
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Williams, H. C., Dellavalle, R. P., & Garner, S. (2012). Acne vulgaris. The Lancet, 379(9813), 361-372.
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Vañó‐Galván, S., Molina‐Ruiz, A. M., Fernández‐Crehuet, P., Rodrigues‐Barata, A. R., Arias‐Santiago, S., Serrano‐Falcón, C., & Camacho, F. M. (2015). Folliculitis decalvans: a multicentre review of 82 patients. Journal of the European Academy of Dermatology and Venereology, 29(9), 1750-1757.
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Maranda, E. L., Simmons, B. J., Nguyen, A. H., Lim, V. M., & Keri, J. E. (2016). Treatment of acne keloidalis nuchae: a systematic review of the literature. Dermatology and therapy, 6, 363-378.

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Acne Keloidalis Nuchae: Causes, Symptoms & Treatment Options

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