What Is Acne Necrotica?
Acne necrotica is an uncommon condition characterized by follicular-based papules or pustules that often heal with varying degrees of pitted varioliform scars localized to the face and scalp. This disorder is typically seen between 30 and 50, with a slight female predilection. Despite its name, it is not a variant of acne. Acne necrotica has been known since the dawn of the last century. However, in recent literature, it has yet to gain much attention.
What Causes Acne Necrotica?
The exact etiology of acne necrotica is still unknown, although Corynebacterium acnes and Staphylococcus aureus have been isolated from the pustules. It is believed that physical manipulation, such as repeated scratching where the underlying skin is affected by folliculitis, may contribute to acne necrotica. Acne rosacea is another suggested factor.
What Are the Clinical Features of Acne Necrotica?
The acne necrotica is characterized by the development of the papules and pustules to form depressed scars that resemble those seen in smallpox. These lesions may be painful with little to no pruritus. People affected by acne necrotica are usually middle-aged women, although men can also be affected. These lesions tend to occur frequently on the face (frontal hairline), scalp, and nape but can also develop on the chest, nose, and eyebrows. These lesions can, however, be more widespread in the scalp, face, and trunk. Acne necrotica is a recurring condition with outbreaks of a few bumps or several hundred. Research suggests that affected individuals are more likely to be anxious or under tremendous pressure due to esthetics.
How Is Acne Necrotica Diagnosed?
The main basis for diagnosis lies in clinical features and histopathology, which reveals necrotizing lymphocytic folliculitis. This rare disorder should be differentiated from other pustular diseases of the scalp. A biopsy from a primary lesion may be helpful. Biopsy of an umbilicated papul usually reveals a perifollicular lymphocytic infiltrate, resulting in many apoptotic cells and follicular necrosis throughout the follicular sheaths. This leads to the destruction of the follicles. In addition, there is surrounding subepidermal edema and lymphocytic inflammation.
Diagnosis Confirmation:
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The primary differential diagnosis in acne necrotica is acne necrotica miliaris, which is typically confined to the scalp and manifests as superficial excoriated crusts and follicular pustules that are highly pruritic. These lesions do not recover with varioliform scars and have been associated with propionibacterium acnes. Although classified as acne, the primary lesion is not a comedo. Pustules and nodulocystic lesions do not happen in acne necrotica. The epidemiology also varies from acne vulgaris.
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Hydroa vacciniforme is seen mainly in children and presents as crusted and vesicular lesions clinically. Compared to acne necrotica, hydroa vacciniforme lesions are usually confined to sun-exposed sites, including the face. The individual lesions, however, do recover with varioliform scars. Hydroa vacciniforme has been related to Epstein-Barr virus (EBV), and biopsies may show lymphocytic-rich infiltrates with intraepidemal reticular vesicles. Unlike acne necrotica, the lymphocytes are not folliculocentric in hydroa vacciniforme.
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Rosacea must also be considered due to facial location, follicular lesions, age distribution, and evident response to Tetracycline therapy observed with acne necrotica. Rosacea can also demonstrate lymphocytic folliculitis on biopsy, but usually, there are additional findings of mixed dermal inflammation with edema and telangiectasia. Scalp and extra facial lesions, the scarring pattern, and the lack of flushing in acne necrotica are distinguishing features.
What Are the Systemic Implications and Complications?
There are no known systemic associations of acne necrotica. The main complication is the evolution of varioliform scars, which are disfiguring and can lead to frontal alopecia.
What Are the Treatment Options for Acne Necrotica?
Topical Therapy:
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Erythromycin gel.
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Hydrocortisone cream.
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Clindamycin or benzoyl peroxide gel.
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To reduce the bacterial load on the body and scalp, topical antibiotics (Mupirocin) can be applied to the axillae, nares, and groin.
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The use of an antibacterial wash can also be considered in resistant cases.
Systemic Therapy:
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Doxycycline.
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Isotretinoin.
Optimal Therapeutic Approach:
There are only a few journals concerning the therapy of acne necrotica. Furthermore, there are no extensive studies due to the apparent rarity of this condition, mainly if strictly-defined criteria are applied. Currently, treatment is based on medications used to treat acne or rosacea. The individual lesions spontaneously heal. Also, repeated episodes of acne necrotica make therapeutic evaluation challenging. In severe cases, the lesions heal with scars, causing permanent hair loss when the scarring extends into the skin's subcutaneous layer (fat layer). Although there are positive responses to these measures, there is no known data about long-term follow-up. Due to the intermittent episodes, treatments may need to be restarted. Oral Isotretinoin should only be recommended for severe acne necrotica cases and incomplete responses to topical preparations and antibiotics.
Follow-Up:
Currently, there are no evidence-based guidelines. Treatment responses should be assessed after six to eight weeks. The leading indicators remain the resolution of lesions and the absence of new ones. Oral antibiotics or Isotretinoin should be discontinued once the lesions have resolved. The possibility of cosmetic surgery for scars can be considered once the condition has improved, but this can be delayed for about four to six months to exclude further flares. The main clinical problem is the rarity of the disease and the lack of information about its etiology and long-term perspective. Some cases may be reclassified as new signs emerge or as results of further biopsies, cultures, or molecular studies leading to a greater understanding of etiopathogenesis.
Conclusion:
Acne necrotica is an uncommon condition characterized by follicular-based papules or pustules that often heal with varying degrees of pitted varioliform scars localized to the face and scalp. The cause of acne necrotica is still unknown, the disease is rare, and there is no information on risk factors. It often occurs in middle-aged women. Treatment is centered around topical and systemic therapies, which can be used long-term for hair follicle disease, decrease bacterial load, and minimize inflammation.
