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MISCELLANEOUS

Acne keloidalis nuchae

Etiology and pathogenesis

Acne keloidalis nuchae (AKN) is a chronic, progressive, keloidal scarring process of the nape of the neck in dark-skinned men. Onset is usually after puberty, and most patients present in the second or third decade. Despite the name, acne vulgaris does not appear to be associated. Infection can contribute greatly to the inflammation and scarring but is thought to be a secondary event. The coexistence of pseudofolliculitis barbae has been noted in many patients, implying an underlying predisposition to both disorders, although there is no clinical or histologic evidence of recurving of superficialhairs into the skin in AKN.

Clinical

Clinically, the patient presents with a follicular pustular eruption on the nape of the neck (Fig.10.38). Comedones are not seen. Later, firm follicular papules develop. Large keloids with sinus tracts, pus, and scarring alopecia may form (Fig. 10.38). Inside the keloidal nodules are crypts of trapped hairs. Often, these groups of hairs emanate from one opening (tufted hairs or polytrichia).

    Pustules, crusting, and drainage are usually manifestations of a secondary infectious component, but at times, the inflammation is non-infectious and cultures are sterile. When a bacterium is found, it is usually S. aureus. The occipital posterior hairline is the overwhelmingly preferred location, but in one study, 3% had parietal lesions.

Differential diagnosis

    Traumatic causes of keloid may need to be considered if there is a solitary confluent lesion without the semiconfluent follicular papules that are commonly seen. Simple ingrowing hairs (pili incurvatum) or follicular infection may be considered in early lesions. Generally, however, there is little diagnostic doubt.

Treatment

The hair should be allowed to grow long in the affected area. Some patients staunchly resist this advice, as they are fond of the shaved look. Mechanical irritation by a tight collar should be avoided if possible, although some patients find this difficult because of the professional attire required by their work. The patient should be encouraged not to pick or squeeze lesions. To control the infectious component, either topical antibiotics (e.g. clindamycin or erythromycin) or oral antibiotics (e.g. tetracycline or oxytetracycline 500mg twice daily, doxycycline 100mg twice daily, or minocycline 100mg twice daily) should be given. If any pustules are present, bacterial culture should be done to assure that an appropriate antibiotic is being used. Hair oils should be avoided.

    Sometimes the inflammatory or infectious component, or both, resist the above measures. It may be that previous scarring has created pockets of infection that are not fully exposed to therapy. Rotation of antibiotics, reculture, and even a course of isotretinoin may be needed. Once the inflammation has been controlled, as evidenced by the absence of pustules, crusting, or pain, the keloids may be treated by injection with triamcinolone (10 - 40mg/mL every 4 weeks). If significant shrinkage of lesions is not obtained after three or four injections, a surgical approach may be tried. Some success may be achieved with shaving lesions flat, followed by postoperative intralesional corticosteroid therapy (e.g. triamcinolone 20 - 40mg/mL every 2 - 4 weeks) combined with a potent or very potent topical steroid (e.g. clobetasol propionate) and an oral antibiotic. However, this approach is not nearly as reliable as those that remove diseased tissue to the subfollicular level. In fact, larger keloids may result. Small, papular lesions may be removed via punch biopsy (e.g. using a hair transplant punch down to ?fibrous tissue). The CO₂laser may be used effectively if removal is carried out to a subfollicular depth. Healing should be allowed to occur through secondary intention. In patients not responding to more conservative therapies and who don't mind permanent loss of hair, laser-assisted epilation should be considered.

    Definitive therapy of severe disease with large keloids and sinus tracts is obtained by surgical debulking. The best results in one study were achieved with horizontal elliptic excision including the posterior hairline down to muscle fascia or the deep subcutaneous tissue (Fig.10.39).

     The wound may be allowed to heal by secondary intention. Alternatively, primary closure after wide undermining for smaller lesions, and the use of a tissue expander inserted above the keloid for larger lesions, may be done. It cannot be overemphasized that any excision or destruction must be carried out to the subfollicular depth. If any portion of the hair follicle is left, recurrence is common and wound contraction is not as great.

    The patient should be informed that the goal of such therapy is an asymptomatic but alopecic scar.

Figure 10.37  Acne conglobata. (a) Longstanding acne conglobata of the cheeks leads to this characteristic appearance of multiple pitted scars. (b) Large inflammatory nodules may occur. If fluctuant, they may be drained. If not, intralesional triamcinolone may be used. (c) The comedo with multiple openings (?stulated comedo) is characteristic of acne conglobata. It forms by multiple sebaceous follicles merging via an inflammatory process and represents a scar. The only effective treatment is unroo?ng of the cavity. (d) A wooden stick pushes through the lesion, illustrating the connection between the openings and the keratinous debris within.

Chloracne

Etiology and pathogenesis

Chloracne results from poisoning by halogenated aromatic compounds. These agents are prevalent in agriculture.

Clinical

Multiple comedones are concentrated over the malar eminences and retroauricular areas in chloracne. In severe cases, comedones may appear on the trunk and extremities. Large cysts may develop. Central nervous system symptoms such as headache and fatigue are usually associated with acute exposure, whereas peripheral sensory neuropathy may represent a late complication. Xerosis, folliculitis, and cystic lesions may be seen.

Differential diagnosis

This diagnosis should be considered if there is acne predominantly around the ears, although ordinary acne may occasionally occur to a significant extent on the retroauricular skin. Comedones within the concha of the ear may occur in discoid lupus erythematosus, but other lesions in the acne spectrum are absent in this condition.

Figure 10.38  Acne keloidalis. (a) Acne keloidalis nuchae (AKN) in a dark-skinned man. The nape of the neck is the usual location for this papular condition of young, dark-skinned men. Short hair and trauma (e.g. football helmets and scratching) predispose. (b) Pustules and papules are characteristic of early lesions. (c) AKN in a pale-skinned man. White men may rarely be affected. (d) Large keloidal lesions may form. Tufts of hair may emanate from multiple openings. Surgical excision is needed here.

Figure 10.39  A horizontal elliptic excision of acne keloidalis nuchae down to the subfollicular depth may be done.

Treatment

Slow resolution often occurs after cessation of the exposure. All forms of conventional acne therapy may be tried. Light cautery after topical anesthesia (e.g. EMLA) has been used.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.