Acne necrotica of the scalp: What is it?

Acne necrotica varioliformis and acne necrotica miliaris

Acne necrotica varioliformis (ANV) - DEEP SCARRING FORM

Acne necrotica varioliformis is thought to be rare but it’s probably way more common than we realize. We just don’t speak of this entity much anymore. Patients with acne necrotic varioliformis develop crops of 1-2 mm papules (bumps) or pustules (“pimples” - except they don’t have pus) that end of healing over with formation of a pitted scar. (varioloform means resembling chicken pox or variola).

When the lesions on ANM first start they look like a red bump but soon form an umbilicated lesions that then goes on to form a pustules and then a crust and then scar. Patients affected by ANV are typically middle aged women (although men can be affected as well) and develop these lesions most often on the face (frontal hairline), scalp, nape but also can develop them on the chest and nose, eyebrows (interestingly in a seborrheic distribution). They can however be more widespead in the scalp, face and trunk. The condition can come and go for years (i.e. a recurrent process) with outbreaks of just a few such bumps or several hundreds. Some of the literature (mainly a 1988 article by Dr David Fisher) cites that affected patients are more likely to be anxious, or under great pressure - but this has not be firmly established. 

The diagnosis of ANV is usually made clinically - meaning that an experienced physician can make this diagnosis by looking carefully at the frontal hairline, scalp, forehead/face and nose and chest and eyebrows.   Pitted scars is the key finding that I look for. This an often be found on the back of the scalp but really anywhere where the disease has affected including the lateral eyebrow. A biopsy can be helpful if there is uncertainty. Biopsy of an umbilicated papule typically shows a lymphocytic infiltrate around the hair follicle and this results in massive death (necrosis) of the keratinocytes in the follicular sheath. Rather than the focal inflammation in the outer portion of the follicle in lichen planopilaris, the inflammation in ANV is widespread throughout the keratinocytes in the sheath. The inflammation may spread into the epidermis with so called lymphocytic exocytosis and there may be necrosis of the epidermis too. In addition to what is happening in the follicle itself, there is also surrounding fluid accumulation (subepidermal edema) and lymphocytic inflammation as well. 

In recent years, there has been a trend to call the condition lymphocytic necrotizing folliculitis. Terms such as acne frontalis are still used. 

Treatment of Acne Necrotica Varioliformis

The treatment of ANV generally begins once the lesions have been cultured. I generally recommend starting with cultures before any type of antibiotic is given. If the culture comes back with an organisms, one can determine the appropriate antibiotic as this information is typically provided by the microbiology lab. If the cultures come back negative, one can begin empirical therapy with topical options like topical clindamycin lotion, topical erythromycin gel and possibly a steroid as well. If ineffective, the dermatologist will generally prescribe an oral agent such as doxycycline (50-100 mg twice daily) or isotretinoin (at a dose of 0.5 mg per kg). Options such as cephalexin or trimethoprim-sulfamethoxasole can be considered as well. I do believe, as do others, that it is imperative to stop the itch scratch itch cycle in this condition. Antihistamines can be considered as can low dose SSRI or SNRI antidepressants. If these antidepressants do not help, doxepin or tricylic antidepressants (amitriptyline 10-25 mg at night can be considered). 

In order to reduce the bacterial load on the body and scalp, topical antibiotics (mupirocin) can be applied to the nares, axillae, and groin. The nails should be trimmed very short. The use of an antibacterial wash can also be considered in resistant cases. 

Acne necrotica miliaris (ANM) - SUPERFICIAL FORM

The diagnosis of acne necrotica “miliaris” must also be considered in all patients with acne necrotica “varioliformis”. However, patients with ANM usually ONLY have a few lesions on the scalp at any one time -although frontal hairline, face and chest can be affected in some patients). By ‘few’ I mean 8-10. The back of the scalp can particularly be affected. The scalp is the main site compared to ANV where the chest and face, eyebrows are also affected. The lesions appear as superficial exocoriated crusts and papules that are extremely itchy. They can resemble pimples although it’s difficult to actually squeeze anything out of them. In fact, it’s usually difficult to find the actual pimple lesions because they have crusted over. The lesions in ANM do NOT heal with scars - and that’s the key differentiating factor from ANV. A link between bacteria such as Propionibacterium acnes or Staphylococcus aureus and ANM has been proposed. Many researchers feel that ANM is simply a form of P acnes folliculitis of the scalp

Treatment of Acne necrotica miliaris (ANM)

Treatment of ANM is similar to ANV with topical steroids, topical antibiotics, and oral tetracyclines being helpful.

FINAL COMMENTS

ANV is more common than we all realize. We just don’t talk about this condition anymore. The dermatologists Plewig and Kligman summarized it best in their 1993 textbook when the stated "Awareness of this bizarre disease is a prerequisite for an accurate diagnosis."

Reference

Fisher DA. Acne necroticans (varioliformis) and Staphylococcus aureus. J Am Acad Dermatol. 1988;18:1136-1138.

Kossard S, Collins A, McCrossin I (1987) Necrotizing lymphocytic folliculitis: the early lesion of acne necrotica (varioliformis). J Am Acad Dermatol 16:1007–1014.

Pitney et al. Acne necrotica (necrotizing lymphocytic folliculitis): An enigmatic and under-recognised dermatosis. Australas J Dermatol. 2018 Feb;59(1):e53-e58.

Plewig G and Kligman AM, eds. Acne and Rosacea. 2nd ed. New York,NY: Springer Verlag NY Inc; 1993:500-505.