Little can be added clinically to Adamson's description of AKN in 1914. The eruption occurs on the upper posterior neck in the form of a raised transverse band at the lower margin of the hairy scalp. The band is usually dusky red in color, smooth and firm to the touch, and of keloidal consistency. It is hairless except at its upper margin, which is abrupt, broken into nodules and fringed with hair in tufts, like aigrettes, or the bunches of bristles in a brush. There may be pustules or crusted nodules here and there along the upper border. The lower margin slopes gradually to the normal skin. Usually there are no comedones or follicular pustules of acne when the patient comes under observation, and there may or may not be a history of acne of the face in youth. Often the patient complains of itching at the site of the eruption.
Pathophysiology: The exact cause of AKN is still speculative. Injury produced by short haircuts (especially when the posterior hairline is shaved with a razor, a practice common in African American men) and curved hair follicles (analogous to pseudofolliculitis of the beard in African Americans) may be the precipitating factors. Other frequently suggested etiologic possibilities are constant irritation from shirt collars, chronic low-grade bacterial infections, and an autoimmune process (AKN usually responds to systemic steroid therapy). The use of antiepileptic drugs and an increased number of mast cells in the occipital region have also been indicated as causes.
The recent findings of Sperling et al indicate that AKN is a primary form of scarring alopecia. Many of the histologic findings closely resemble those found in certain other forms of scarring alopecia. They claim that overgrowth of microorganisms does not play an important role in the pathogenesis of AKN. They also found no association between pseudofolliculitis barbae and AKN.
Herzberg et al provided another explanation based on extensive transverse microscopy, histochemistry, and electron microscopy. Herzberg et al described the following hypothetical sequence of inflammatory events that take place in AKN:
The acute inflammation, whether it begins in the sebaceous gland or elsewhere in the region of the deep infundibular or isthmus levels, is a cause or the result of a weakened follicular wall at these levels. This enables the release of hair shafts into the surrounding dermis. The "foreign" hairs incite further acute and chronic granulomatous inflammation. The localized granulomatous inflammation manifests itself clinically as a papular lesion. Fibroblasts lay down collagen and scars form in the region of the inflammation. Distortion and occlusion of the follicular lumen by fibrosis leads to hair retention in the inferior follicle and further smoldering granulomatous inflammation and scarring. The scarring and granulomatous inflammation manifest themselves clinically as keloidlike scars and plaques.
They also found that the follicular lymphocytic infiltrate contained a mixed B- and T-cell population and that the plasma cell immunoglobulins are of a polyclonal nature.
Frequency:
- In the US: AKN is said to represent 0.45% of all dermatoses affecting black persons.
Mortality/Morbidity: AKN is a medically benign but often psychologically devastating dermatosis. Squamous cell carcinoma has developed secondary to radiation therapy in rare cases. Chronic pruritus, scarring, and drainage may occur. Without therapy, the lesions may continue to enlarge and sometimes coalesce, and new ones may appear. Scarring alopecia of the involved scalp is a common finding.
Race: AKN most often occurs in African Americans. Hispanics are the next most common group, followed by Asians and (least often) whites.
Sex: Although the early literature inferred that AKN occurred only in males, it is now known to occur in females. The male-to-female ratio is approximately 20:1.
Treatment
Medical Care: After a thorough history, obtain a specimen for bacterial culture and sensitivity. A biopsy should be performed if the presentation is not typical.
- Removing each papule with a hair transplant punch is the next therapeutic option if combined retinoic acid/corticosteroid treatment is not successful. The punch should extend deep (past the deepest level of the hair follicle) into the subcutaneous tissue, as superficial removal seems to have a much higher incidence of recurrence. After removal, inject the wound edges with a bolus of Kenalog 40 mg, and, then, it should be closed with 4-0 sutures. Or, use an equal amount of 2% lidocaine with epinephrine and triamcinolone acetonide at 40 mg/mL to anesthetize the surgical site.
- The ends of the nylon sutures often irritate the skin if patients sleep on their back or have a short neck. Use silk sutures to prevent this problem. Instruct patients to clean the postoperative area 3 times a day with alcohol or sodium chloride solution followed by the application of a topical antibiotic ointment.
- Remove the sutures in 6-14 days, and start patients on a twice-daily topical retinoic acid/corticosteroid regimen for 4-6 weeks.
- Kenalog (10-40 mg/mL) is also injected into the postoperative site or sites every 2-3 weeks for 4 sessions, starting 1 week after suture removal.
- Postoperative care is the same as with punch grafts.
- The postoperative site often splays to the diameter of the initial excision. Always remember when closing primarily not to close when the posterior part of the neck is flexed or patients will spend a week or more having to look upward. Under this amount of tension, the resultant scar splays and will be the same size as the amount of area removed, often creating an area of alopecia as large as the initial defect.
- Prior to performing surgery, tell both the patient and the caregiver providing the postoperative care (clean postoperative site twice a day with alcohol or sodium chloride solution, and apply an antibiotic ointment) that the postoperative site will be cosmetically unacceptable initially, and the patient will experience pain and discomfort for the first few days.
- Complete wound healing takes 8-12 weeks. Give patients explicit verbal and written postoperative care instructions.
- If possible, show patients and postoperative caregivers a set of photographs showing the before; immediate postoperative, 1-week postoperative, and monthly postoperative healing progression; and final healing.
- Initiate a broad-spectrum antibiotic (eg, erythromycin) on the day of surgery and continue for 10 days because sterilizing the scalp is impossible.
- Tie off or coagulate all bleeders after excision. Then, apply pressure to the postoperative site for 10 minutes, and check for bleeding again. If most of the oozing has stopped, apply an antibiotic ointment to minimize bacterial colonization, and place a nonadherent dressing (eg, Telfa, Vaseline gauze, adaptic) over the defect. Wrap gauze over the dressing to help secure it and absorb the exudate. Use paper tape to secure the gauze.
- Pain medication may be necessary for the first 48 hours.
- Have patients return in 24-36 hours (preferably with the person responsible for changing dressings) for removal of the initial dressing. Soak the area with sodium chloride solution not only to facilitate the removal of the dressing but also to clean the postoperative site.
- Instruct patients to start cleaning the site twice a day (following the regimen above) once the dressing is removed.
- Instruct patients to return for follow-up visits in 1 and 3 weeks or sooner if any complications occur. Visits thereafter are necessary only on an as-needed basis.
- Instruct patients to return for follow-up care for possible initiation of topical steroid/retinoic acid therapy once the area has healed, usually in 2-3 months.
- A follicular papule or pustule occasionally develops along the border of the linear scar. Treat all inflammatory lesions with topical clindamycin until the infection subsides and then remove the lesions with the hair transplant punch method.
- Excision with grafting is not as cosmetically acceptable because it results in a large depressed non–hair-bearing area.
- Optimal healing with second intention healing is achieved when the excision is a horizontal ellipse of the posterior part of the scalp, including the posterior part of the hairline, and extends to the level of the muscle fascia or the deep subcutaneous tissue.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Drug Category: Corticosteroids -- These agents have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli. Class 2 or 3 topical steroid creams or gels (eg, Elocon cream, topical cream or gel, Lidex cream or gel) may be mixed with equal parts of retinoic acid; this should be applied bid.
| Drug Name | Triamcinolone acetonide (Kenalog, Amcort) -- For inflammatory reactions responsive to steroids; decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing capillary permeability. |
|---|---|
| Adult Dose | 10-40 mg/mL injected in postoperative sites q2-3wk for 4wk |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; fungal, viral, and bacterial skin infections |
| Interactions | Coadministration with barbiturates, phenytoin, and rifampin decreases effects |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Multiple complications (eg, severe infections, hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression) may occur; abrupt discontinuation of glucocorticoids may cause adrenal crisis |
| Drug Name | Prednisone (Deltasone, Meticorten, Orasone) -- May decrease inflammation by reversing increased capillary permeability and suppressing PMN activity. Used when patient has acute flare. |
|---|---|
| Adult Dose | 40-80 mg PO every morning |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; viral, fungal, tubercular skin, or connective tissue infections; peptic ulcer disease; hepatic dysfunction; GI disease |
| Interactions | Coadministration with estrogens may decrease clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use |
| Drug Name | Clobetasol propionate (Olux foam) or Mometasone (Elocon) -- May depress formation, release, and activity of endogenous chemical mediators of inflammation. Available as 0.025%, 0.05%, and 0.1% cream (Elocon) and as a 0.05% foam (Olux). |
|---|---|
| Adult Dose | Mix with equal parts of retinoic acid and apply bid sparingly to affected areas; do not use occlusive dressing |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; fungal, viral, or tubercular skin lesions; herpes simplex or herpes zoster |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Use over large or denuded areas of the body for prolonged periods of time with an occlusive dressing or on infants may produce adverse systemic effects |
| Drug Name | Fluocinonide (Lidex, Fluonex) -- High-potency topical corticosteroid that inhibits cell proliferation; has immunosuppressive and anti-inflammatory properties. |
|---|---|
| Adult Dose | Mix with equal parts of retinoic acid and apply bid sparingly to affected areas; do not use occlusive dressing |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; herpes simplex infection; fungal, viral, or tubercular skin lesions |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | May cause adverse systemic effects if used over large areas, denuded areas, on occlusive dressings, or during prolonged treatment periods |
| Drug Name | Tretinoin (Retin-A) -- Inhibits microcomedo formation and eliminates existing lesions. Makes keratinocytes in sebaceous follicles less adherent and easier to remove. Available as 0.025%, 0.05%, and 0.1% creams. Also available as 0.01% and 0.025% gels. |
|---|---|
| Adult Dose | Mix with equal parts of a class 2 or 3 corticosteroid cream or gel and apply bid |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Toxicity increases with coadministration of benzoyl peroxide, salicylic acid, and resorcinol; avoid topical sulfur, resorcinol, salicylic acid, other keratolytics, abrasives, astringents, spices, and lime |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Photosensitivity may occur with excessive sunlight exposure; caution in eczema; do not apply to mucous membranes, mouth, and angles of nose |
| Drug Name | Erythromycin (E-Mycin, Erythrocin) -- Inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest. For treatment of staphylococcal and streptococcal infections. Age, weight, and severity of infection determine proper dosage in children. When bid dosing is desired, half-total daily dose may be taken q12h. Double the dose for more severe infections. |
|---|---|
| Adult Dose | 250 mg PO qid taken for 10 d postoperatively to prevent infection |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; hepatic impairment |
| Interactions | Coadministration may increase toxicity of theophylline, digoxin, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | Caution in liver disease; estolate formulation may cause cholestatic jaundice; GI adverse effects are common (give doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur |
| Drug Name | Mupirocin (Bactroban) -- Topical antibiotic; inhibits bacterial growth by inhibiting RNA and protein synthesis. |
|---|---|
| Adult Dose | Apply topically bid |
| Pediatric Dose | Apply as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | None reported |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | Prolonged use may result in the growth of nonsusceptible organisms |
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