Acne Necrotica Miliaris is a superficial, non-scarring inflammatory disorder of the hair follicles. It is one of two syndromes that falls under the broader clinical term Acne Miliaris Necrotica (AN), the other being the deeper, scarring Acne Necrotica Varioliformis. Since first being described in 1851, AN has proven to be a rare condition, prevalent among adult males, with chronic symptoms that wax and wane over time.
Both Acne Necrotica Miliaris and Acne Necrotica Varioliformis are characterized by pruritic follicular papule that are often triggered by stress.1 Patients tend to be men aged 30 to 50, although the lesions have been reported in women and patients younger than 30 who have passed puberty.
Acne Necrotica Miliaris is characterized by minute, intensely itchy pustules on the scalp that may become sore and crusted due to constant scratching.2 The lesions may concentrate around the frontal hairline (acne frontalis), but can appear anywhere on the scalp. They also vary in number from just a few to numerous pustules covering the scalp. Additional lesions may be found on the face, neck, chest, or back.3
Acne Necrotica Miliaris affects only the superficial portion of the hair follicle, allowing for hair regrowth following successful treatment, which can include oral antibiotics, topical corticosteroids, and oral isotretinoin, which has shown a rapid reduction of the pruritic lesions.4
Acne Necrotica Varioliformis is characterized by erythematous follicular papules that undergo necrosis (or cell death). These deeper lesions may progress to crusting, dry, dark scabs that leave smallpox-like scars (varioliformis) in their wake. Permanent hair loss may occur where the scalp has
been scarred (cicatricial alopecia).
Histological studies of an early lesion show lymphocytes (white blood cells) and plasma cells centered around a central hair follicle. The lymphocytes then fuse into the external root sheath. The keratinocytes within the external root sheath and surrounding epidermis show extensive cell necrosis.5
The true etiology, or cause, of AN is unknown, however, it has been postulated that the initial lesions are inflamed hair follicles with Propionibacterium acnes. (Propionibacterium acnes are slow growing anaerobic bacterium which are linked to the skin condition acne.6 They are gram positive, which means they stain dark blue or violet with gram staining. Gram positive bacteria generally have a single lipid bilayer called monoderms.)
The lesions may also be caused by an abnormal reaction to the Staphylococcal Aureus Bacteria and the Streptococcal Bacteria, which live on the skin at all times but can cause infection when they enter the body through a cut or other injury. Gram-negative bacteria, which usually originates in the nose following antibiotic treatment for acne, may also be to blame, as is Tinea Capitis (ringworm of the scalp), caused by a fungus that invades the hair shaft. In at least one case, use of the drug phenylbutazone was believed to have caused the syndrome.7 In still others, extreme mechanical manipulation of the scalp due to scratching or rubbing patches of underlying folliculitis may be to blame, as are the tiny parasitic mites, demodex folliculorum. However, the most common pathogens found in pustules remain Staphylococcus aureus and Propionibacterium acnes.8
Examining the scalp and forehead for past umbilicated scars with a “punched-out” appearance is helpful to the trichologist working toward a diagnosis of AN. In addition, the presence of Staphylococcus aureus and Propionibacterium acnes should be determined in erupting pustules. In the case of Propionibacterium acnes, Isotretinoin should be tried, while in the case of Staphylococcus aureus, anti staph agents and oral tetracyclines may prove successful.9
Sources
Dawber, Rodney, Ed., Diseases of the Hair and Scalp, Third Edition, Blackwell Science, Malden, MA, 1997.
DermNetNZ.org
HairScientists.org
Olsen, Elisa A.,Ed., Disorders of Hair Growth, Second Edition, McGraw-Hill, New York, 2003.
Wikipedia.org
1 Dawber, Rodney, Diseases of the Hair and Scalp, p. 511.
2 DermnetNZ, Scalp Folliculitis, http://dermnetnz.org/acne/scalp-folliculitis.html
3 Olsen, Elisa A., Disorders of Hair Growth, p. 111.
4 Olsen, Elisa A., Disorders of Hair Growth, p. 383.
5 Olsen, Elise A., Disorders of Hair Growth, p. 112.
6 Wikipedia.org, Propionbacterium Acnes, http://en.wikipedia.org/wiki/Propionibacterium_acnes
7 Zemite, Inga, http://www.hairscientists.org/acne-miliaris.htm
8 Zemite, Inga, http://www.hairscientists.org/acne-miliaris.htm
9 Zemite, Inga, http://www.hairscientists.org/acne-miliaris.htm
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