Are You Confident of the Diagnosis?
What you should be alert for in the history
Characteristic findings on physical examination include follicular-based papular (Figure 1) or pustular presentation with ingrown hairs and hypertrophic or keloidal scarring on the nape of the neck (Figure 2). Papules or pustules may form confluent plaques with draining sinus tracks. Involved follicles may show tufted hair folliculitis while intact follicles at the margins may demonstrate polytrichia. More advanced or progressive states may demonstrate keloidal formation.
Expected results of diagnostic studies
Skin biopsy: Histopathology of initial acute presentation shows folliculitis with subsequent rupture and destruction of the follicle. The more chronic presentation will demonstrate dense dermal fibrosis with chronic inflammatory cell infiltrate, which includes numerous plasma cells. Hair shafts surrounded by microabscesses and or foreign body giant cells are present in the dermis .
The differential diagnosis includes folliculitis secondary to bacterial infection, especially Staphylococcus, which needs to be excluded. In bacterial folliculitis, the pustular or papular response is more widely distributed across the entire scalp and does not localize to the nape of the neck.
Who is at Risk for Developing this Disease?
In the United States, acne keloidalis nuchae (AKN) occurs most commonly in young Afro-American men, followed in frequency by Hispanic, Asian and less often Caucasian men. Acne keloidalis may occur in women, but the male-female ratio is at least 20:1.
What is the Cause of this Disease?
The definitive etiology of AKN is unknown. No specific genetic factor has been identified. In individuals with tightly curled hair, shaving or trimming the nape of the neck may initiate the presentation of AKN . The association of mild trauma to the hair follicle and subsequent development of a “pseudofolliculitis “ response in the posterior neck region supports an analogous mechanism of action and potential genetic predisposition as presented in the pseudofolliculitis barbae chapter. In one study, two thirds of the AKN-affected population had concomitant seborrheic dermatitis. The persistent irritation and potential trauma from excoriation may initiate the AKN process in those with seborrheic dermatitis.
The pathophysiologic mechanism responsible for acne keloidalis is analogous to that of pseudofolliculitis barbae. Basically, it represents a foreign-body reaction as a result of the hair penetrating the dermis. The actual penetration of the skin can occur through one of two pathways: through the stratum corneum after growing out of the follicle and curling back towards the skin, or by piercing the follicular wall directly.
Systemic Implications and Complications
Optimal Therapeutic Approach for this Disease
Encourage those with AKN to avoid any causes of mechanical irritation to the posterior hairline: no plucking, pulling or close haircutting in the region, with recommended daily brushing of the area to lift hairs that may be regrowing into the surface of the skin.
Topical retinoid such as tretinoin 0.1% cream, topical cortical steroid such as betamethasone diproprionate 0.05%
gel or combination of both.
INFLAMED PAPULES WITH POSTULES
Bacterial cultures to rule out S aureus or methicillin-resistant S aureus (MRSA), topical clindamycin, oral tetracycline, doxycycline or minocycline incombination with Derma-Smoothe oil with monthly follow up to check progress. If no progress is noted, advance therapy. Papules could also be intralesionally injected with triamcinolone monthly with initial TAC 3 mg/kg for small lesion up to TAC 10 – 40 mg/kg for nodularity. Laser hair removal, such as the neodynium: YAG as in pseudofolliculitis barbae patients, is beneficial in AKN. In individuals with culture-positive S aureus, ensure that nasal carriage has been adequately assessed with culture and treated with topical mupirocin . Hibiclens soap could also be induced into the hygienic routine.
NODULES, PLAQUE, OR KELOID DEVELOPMENT
Once hypertrophic scarring has developed, treatment with oral or topical antibiotics is much less successful and measures to control formation of hypertrophic or keloidal scarring must be employed. Potent topical corticosteroid ointments may be helpful, but intralesional injection of triamcinolone can drastically reduce the bulk of scar tissue. Surgical excision with primary closure or for larger lesions, allowing them to heal by secondary intention. In severe cases with plaques larger than10 cm that were unresponsive to triamcinolone injections, monthly 5-fluorouracil injections have demonstrated excellent results.
Sinus tracts may respond to chloramphenicol 500mg in 30 gof fluocinonide ointment/cream, applied three times a day.
Recommend monthly follow-up with aggressive advancement up the noted treatment ladder once there is nodular development.
Unusual Clinical Scenarios to Consider in Patient Management
AKN may be seen with acanthosis nigricans and the metabolic sydrome.
What is the Evidence?
Glenn, MJ, Bennett, RG, Kelly, AP. “Acne keloidalis nuchae: Treatment with excision and secondary intention healing”. J Am Acad Dermatol. vol. 33. 1995. pp. 243-6. (Best results were achieved in excision of AKN with second-intention healing when the excision was a horizontal ellipse of the posterior aspect of ties are the scalp, including the posterior hairline.)
Shockman, S, Paghdal, KV, Cohen, G. “Medical and surgical management of keloids: a review”. J Drugs Dermatol. vol. 9. 2010 Oct. pp. 1249-57. (The authors discussed the five different types of keloid: postincisional, ear lobe, spontaneous, acne keloidalis nuchae (AKN) and sessile. Many medical and surgical modalities have been studied in the treatment of these entities, including silicone sheets, intralesional corticosteroid injections, cryosurgery, ligation, 5-fluorouracil, Allium cepa (onion) extract, lasers, imiquimod, interferon-a and intralesional verapamil and surgical excision.)
Sperling, LC, Homoky, C, Pratt L Sau, P. “Acne keloidalis is a form of scarring alopecia”. Arch Dermatol. vol. 136. 2000. pp. 479-84. (Acne keloidalis is a primary form of scarring alopecia, and many of the histologic findings closely resemble those found in certain other forms of cicatricial alopecia. Extensive disease may be present in patients with AK and can account for some of the permanent hair loss. Overgrowth of microorganisms does not appear to play an important role in the pathogenesis of the disease. There is no etiologic relationship between AK and pseudofolliculitis barbae. Therapies found to be useful in other forms of inflammatory scarring alopecia are useful in the treatment of early acne keloidalis.)
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