Are You Confident of the Diagnosis?
Acne necrotica ( varioliformis) is a rare condition based on the few reports and limited number of cases observed. The term is used to describe crops of follicular-based papules or pustules that heal with pitted varioliform scars localised particularly to the face and scalp.
Characteristic findings on physical examination
The primary lesion is a pruritic andtender red edematous follicular papule or papulopustule that becomes umbilicated, develops a crust, and heals to leave a depressed scar with hair loss (Figure 1,Figure 2). The condition occurs most frequently in middle-aged and elderly individuals and is particularly localized to the frontal hairline, forehead and nose, but can extend throughout the scalp, face and upper trunk. Typically, acne necrotica is a recurrent process that may last for years.
Expected results of laboratory studies
The clinical features have been the main basis for diagnosis but a biopsy from an early lesion may be helpful. Biopsy of an umbilicated papule often shows a prominent perifollicular lymphocytic infiltrate resulting in follicular necrosis and the apearance of numerous appototic cells throughout the follicular sheaths, leading to progressive destruction of the follicles. There is surrounding subepidermal edema and lymphocytic inflammation (Figure 3).
Cultures have isolated staphylococci (Staphylococcus aureus or epidermidis) but the pathogenic significance of these bacteria remains uncertain. Viral samples to exclude herpes should also be taken in acute presentations with grouped lesions.
The main differential diagnosis in acne necrotica (varioliformis) is acne necrotica miliaris, which characteristically is confined to the scalp and presents as superficial excoriated crusts and follicular pustulesthat are extremely pruritic. These lesions do not heal with varioliform scars and have been linked to Propionibacterium acnes.
Although classified as an acne, the primary lesion is not a comedo. Pustules and nodulocystic lesions do not occur in acne necrotica. The epidemiology also differs from acne vulgaris.
The histologic pattern of lymphocytic necrotizing folliculitis is seen particularly in viral associated folliculitis and careful examination for evidence of herpetic cytopathic changes is required. The issue whether acne necrotica may still be related to another virus remains unresolved.
Hydroa vacciniforme is seen particularly in children and presents as crusted and vesicular lesions. In contrast to acne necrotica, the lesions are often confined to sun exposed sites, including the faceThe individual lesions, however, do heal with varioliform scars.
Hydroa vacciniformehas been linked to EBV and biopsies may show lymphocytic rich infiltrates with intraepidemal reticular vesicles. Compared to acne necrotica, the lymphocytes are not folliculocentric in hydroa vacciniforme. A subset of children presenting with hydroa vacciiniforme-like lesions have a more severe form with extensive persistent and indurated lesions that evolves to a lymphoma.
Acnitis (lupus miliaris disseminatus facei) presents as small translucent yellow-brown papules concentrated around the eyelids,cheeks and at times the axillae.The lesions may heal with small scars. In contrast to acne necrotica, the pathology in acnitis is dominated by dermal tuberculoid or sarcoidal granulomas with central necrosis. Although the granulomas can be folliculocentric, this is often difficult to demonstrate.
Rosacea may also need to be considered due to age distribution, the facial location, follicular lesions,and apparent response to tetracycline therapy seen with acne necrotica.Rosacea may also have a lymphocytic folliculitis on biopsy but usually there are additional findings of mixed dermal inflammation with telangiectasia and edema.The lack of flushing, scalp and extrafacial lesions as well as the pattern of scarring in acne necrotica are distinguishing features .
Who is at Risk for Developing this Disease?
Acne necrotica occurs in middle-aged individuals and there is no sex predilection. The condition is rare and there is no information on risk factors.
What is the Cause of this Disease?
The current hypothesis is that this unusual necrotizing folliculitis healing with varioliform scars represents an exaggerated reaction to an organism. Although S aureus has been implicated, the reason why this condition is rarely seen as a sequel to staphylococcal folliculitis remains unexplained.
The primary pathology is a lymphocytic necrotizing folliculitis rather than a pustular folliculitis, casting doubt on the role of bacteria and favoring a virus that has not been identified.
Systemic Implications and Complications
Acne necrotica has no known systemic associations. The main complication is the development of varioliform scars, which are disfiguring and may lead to frontal alopecia.
-Clindamycin 1% lotion or clindamycin/benzoyl peroxide gel.
-Erythromycin 2% gel
-1% hydrocortisone cream
-Doxycycline 50mg twice daily
-Isotretinoin 0.5mg/kg daily
Optimal Therapeutic Approach for this Disease
There are very few publications concerningtherapy of acne necrotica. There are no large studies due to the apparent rarity of this condition, particularly if strictly-defined criteria are applied . Currently, treatment is very much based on agents used to treat acne or rosacea.
The individual lesions spontaneously heal and there are often repeated episodes, making therapeutic evaluation difficult. Although there are apparently positive responses to these measures, there are no data with respect to long-term follow up. It is likely that treatments will need to be restarted due to the intermittent episodes. Oral isotretinoin should be reserved for severe presentations and incomplete responses to topical preparations and antibiotics.
There are no evidence-based guidlines.Treatment responses should be evaluated after 6-8 weeks. The main indicators would be resolution of lesions and absence of new ones.Oral antibiotics or isotretinoin should be discontiued once the lesions have settled and maintenance kept with topical preparations. The possibility of cosmetic surgery for scars could be considered once the condition has settled, but this may need to be delayed for 4-6 months to exclude a further flare.
The family should be informed that the condition is an exaggerated reaction to a follicular organism and despite its name the condition is unrelated to acne vulgaris. There have been no reports of multiple members of families with this condition and it is not contagious
Unusual Clinical Scenarios to Consider in Patient Management
The main clinical conundrum is that this condition is rare and little is known about its pathogenesis and long-term outlook. Some cases may ultimately be reclassified as fresh signs emerge or as results of further cultures, biopsies, or molecular studies lead to a greater understanding of the pathogenesis.
What is the Evidence?
Kossard, S, Collins, A, McCrossin, I. “Necrotizing lymphocytic folliculitis: The early lesion of acne necrotica ( varioliformis)”. J Am Acad Dermatol. vol. 16. 1987. pp. 1007-14. (The authors describe four patients presenting with acne necrotica with umbilicated follicular papules and varioliform scars. Skin biopsies in each case showed a disinctive necrotizing lymphocytic folliculitis.)
Plewig, G, Jansen, T. “Acneiform Dermatoses”. Dermatology. vol. 196. 1998. pp. 102-7. (The authors review the differential diagnoses and management of acneiform dermatoses, including acne necrotica.)
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