Acne necrotica: A real head-scratcher

By Warren R. Heymann, MD, FAAD
May 15, 2024
Vol. 6, No. 20

I sympathize with new residents in dermatology coming to grips with difficult terms and concepts that are essential in practice. As a novice, I recall struggling with the concept of acne necrotica (AN), dreading that I would never understand this disorder. I was intrigued by the colloquial term “tycoon’s scalp,” but otherwise have not given this disorder much thought throughout my career, mostly because I never understood it. I am not alone. Some recent publications have piqued my curiosity to see if the landscape of AN has become clearer.

According to Pitney et al, “Despite its early recognition as a clinical entity by Bazin in 1851, and the milder miliaris variant in 1928 recognized by Sabauraud, this enigmatic disorder is these days considered rare and its authenticity is doubted by some…” (1) Synonyms for AN in the literature include AN miliaris, AN varioliformis, acne frontalis, acne atrophica, pustular perifolliculitis, and necrotizing lymphocytic folliculitis. (2) The earliest article on AN listed in PubMed was by Graham Little (of lichen planopilaris fame!) describing a 55-year-old man with varioliform lesions of the forehead and nape of the neck. The ensuing discussion with his colleagues questioning the diagnosis and treatment options still resonates nearly a century later. (3)

Acneiform eruptions resemble acne vulgaris but are unrelated etiologically. Examples of acneiform eruptions are drug eruptions (most classically steroids and epidermal growth factor inhibitors, among many others), Gram-negative folliculitis, acne aestivalis, and AN. (2,4)

Zirn et al summarize the clinical attributes of AN, noting that the disorder has been traditionally divided into a superficial, abortive variant, termed AN miliaris, and a deep, scarring form called AN varioliformis. Most patients are between the ages of 30 and 50 years with a slight male predilection. AN usually manifests as very pruritic, pinhead-sized vesiculopustules, becoming rapidly excoriated to form crusted erosions. Lesions are usually confined to the scalp and follow a protracted waxing and waning course. AN varioliformis is characterized by pea-sized, follicular-based, reddish-brown, umbilicated papules that undergo central necrosis to form erosions with adherent hemorrhagic crusts that shed after 3 to 4 weeks, with residual depressed, varioliform scars. Lesions typically involve the hairline of the scalp, notably along the forehead, temples, eyebrows, nose, and cheeks; infrequently, the midchest and interscapular region are affected. The course is relentless over many decades, frequently resulting in severe, disfiguring scars. An overlap of AN miliaris and AN varioliformis has been described. (5)

Green et al performed a systematic review of AN encompassing a total of 74 patients from 19 studies. Most patients were female (n = 51/74, 68.9%) with an average age of 51.9 years. The most common locations of lesions were the face (n = 42/61, 68.9%), scalp (n = 33/61, 54.1%), and trunk (n = 23/61, 37.7%). The diagnosis of AN was most often made clinically and histologically, with histology showing perifollicular necrosis and lymphocytic infiltrate (n = 42/74, 56.8%). (6)

There are no systemic associations with AN, although Fisher observes that patients admit to being “highstrung” or intensely anxious. (7) (Could this be the reason behind the moniker “tycoon’s scalp?”) AN was reported in a 25-year-old woman with systemic lupus erythematosus, systemic sclerosis, and hypothyroidism; the authors acknowledge that this may be coincidental. (8)

In their critical study of AN histology in four patients, Kossard et al state: “The pathologic findings were dominated by lymphocytic inflammation around centrally placed follicles evolving to follicular necrosis that extended to the perifollicular epidermis and dermis. Early lesions showed the development of multiple individual necrotic keratinocytes within the follicular sheath and adjacent epidermis with lymphocytic exocytosis. Later lesions showed more intense necrosis and scale crust obscuring the central target but were still dominated by a peripheral lymphocytic infiltrate. The early pathologic findings of acne necrotica (varioliformis) are represented by a necrotizing lymphocytic folliculitis and differ from the pattern seen in association with nonspecific excoriations, acute bacterial folliculitis, classic comedogenic acne, or acnitis [lupus miliaris disseminatus faciei].” (9)

The etiology of AN is obscure, although Propionibacterium (Cutibacterium) acnes and Staphylococcus aureus have been implicated. Fisher suggested that excoriation of lesions may further the process. (6,7). Therapeutic maneuvers include antibiotics (topical and systemic), steroids (topical and systemic), retinoids (topical and isotretinoin) with variable results. Doxycycline is considered a first-line option.

More than 40 years in dermatology have taught me that I might be able to put a name on a disorder, but that does not mean I understand it. In retrospect, I am not sure if I have ever encountered AN varioliformis but have probably seen many cases of AN miliaris, just calling it folliculitis, without confirmatory biopsies. Look at the image of the patient I coincidentally saw today (above) — a 36-year-old man who works as a financial analyst (a tycoon?) — he scratches his scalp because it itches while I scratch mine out of ignorance.

Point to Remember: Acne necrotica is a puzzling, under-recognized disorder that may be very distressing for afflicted patients. Further research into the pathogenesis of this lymphocytic folliculitis is warranted so that more specific therapies can be developed.

Our experts’ viewpoints

Steven Kossard, FACD, PhD, FAAD
Director, Kossard/Laverty Dermatopathologists
Macquarie Park, NSW Australia

Acne necrotica varioliformis has remained rare despite the potential role of identifying further cases linked to the histopathology defined as necrotizing lymphocytic folliculitis. In 1987, there was a spate of four cases and the histopathology and clinical presentation both appeared to hold the key to further defining this entity initially described by Graham Little. I felt sure I would discover further cases! Forty-five years have passed since that publication, and I have not seen further cases in clinical practice. This histopathology, while uncommon, did not lead to diagnosing additional cases. Isolated cases have been published under this title. I am puzzled by this situation and can only assume that the presentations possibly had a “viral” basis but there were no cytopathic features for herpes. The much more common “tycoon scalp,” acne necrotic miliaris, has rather nonspecific histopathology which is pustular and usually lesions are excoriated and not biopsied. The mystery continues and I am none the wiser despite my early anticipation that I had made headway in 1987 in the acne necrotica field!

Howard Maibach, MD, FAAD
Professor, Dermatology
University of California, San Francisco

Nadia Kashetsky, MD, MSc
Dermatology Resident
University of British Columbia Department of Dermatology and Skin Science

Maxwell Green, MPH
MD Candidate, 2024
Tulane University School of Medicine

Aileen Feschuk
MD Candidate, 2024
Memorial University of Newfoundland

Acne necrotica is a descriptive diagnosis — present in standard textbooks for some decades. It is clinically identified as white pustules and small red papules — most frequently on the scalp but can occur elsewhere.

The usual history is of recurrent lesions, responsive to oral tetracyclines — but often eventually recurs in spite of such therapy. Microbial cultures typically reveal Staphyloccus aureus and normal skin flora. This is because the cultures are usually aerobic.

Smears of the pustules reveal gram-positive pleomorphic rods, most likely suggestive of Cutibacterium acnes. Cultures in the literature do not verify this — as this is a strict anaerobe not routinely utilized in many skin microbiology labs.

Therapy consists of isotretinoin — with occasional recurrences requiring another isotretinoin course. The demonstration of C. acnes on smear does not prove but suggests a causal relationship of the clinical lesion to this organism. The Koch’s postulates have not confirmed this relationship, but common sense and the response to isotretinoin suggests this relationship. No one has tried to reproduce the lesions in animals by applying C. acnes in an animal or human models. Many mysteries remain to be resolved for not only acne necrotica but also acne vulgaris. Namely, what determines susceptibility in one individual to another — in this uncommon clinical entity in the acne necrotica is uncommon frequency, and in both entities, what determines which hair follicle develops the pustule, whereas the overwhelming majority do not. Dermatology has much to learn in this and other areas.

1. Pitney LK, O'Brien B, Pitney MJ. Acne necrotica (necrotizing lymphocytic folliculitis): An enigmatic and under-recognised dermatosis. Australas J Dermatol. 2018 Feb;59(1):e53-e58. doi: 10.1111/ajd.12592. Epub 2017 Feb 27. PMID: 28240342.

2. Plewig G, Jansen T. Acneiform dermatoses. Dermatology. 1998;196(1):102-7. doi: 10.1159/000017841. PMID: 9557242.

3. Little EG. Acne Necrotica. Proc R Soc Med. 1928 Feb;21(4):674-5. PMID: 19986326; PMCID: PMC2102033.

4. Fabbrocini G, Panariello L, Caro G, Cacciapuoti S. Acneiform Rash Induced by EGFR Inhibitors: Review of the Literature and New Insights. Skin Appendage Disord. 2015 Mar;1(1):31-7. doi: 10.1159/000371821. Epub 2015 Feb 13. PMID: 27171241; PMCID: PMC4857844.

5. Zirn JR, Scott RA, Hambrick GW. Chronic acneiform eruption with crateriform scars. Acne necrotica (varioliformis) (necrotizing lymphocytic folliculitis). Arch Dermatol. 1996 Nov;132(11):1367, 1370. doi: 10.1001/archderm.132.11.1367. PMID: 8915319.

6. Green M, Feschuk A, Kashetsky N, Maibach H. Clinical characteristics and treatment outcomes in acne necrotica. Int J Dermatol. 2023 Sep;62(9):e471-e472. doi: 10.1111/ijd.16595. Epub 2023 Jan 22. PMID: 36683196.

7. Fisher DA. Acne necroticans (varioliformis) and Staphylococcus aureus. J Am Acad Dermatol. 1988 May;18(5 Pt 1):1136-8. doi: 10.1016/s0190-9622(88)80019-7. PMID: 2968375.

8. Barrera-Godínez A, Oliveros-Hernández AF, Gatica-Torres M, Martínez-Benitez B, Dominguez-Cherit J. Acne Necrotica in a Woman With Systemic Lupus Erythematosus and Systemic Sclerosis. Cureus. 2022 Mar 9;14(3):e23008. doi: 10.7759/cureus.23008. PMID: 35464589; PMCID: PMC9001242.

9. Kossard S, Collins A, McCrossin I. Necrotizing lymphocytic folliculitis: the early lesion of acne necrotica (varioliformis). J Am Acad Dermatol. 1987 May;16(5 Pt 1):1007-14. doi: 10.1016/s0190-9622(87)80408-5. PMID: 2953765.

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