A 12-year-old with a perplexing rash

THE CASE

The parents of a healthy 12-year-old boy bring him for a second opinion. He was diagnosed with pityriasis rosea 6 months ago, and new lesions, which are occasionally a little itchy, keep appearing. What is causing these new lesions? 

DERMCASE diagnosis: PITYRIASIS LICHENOIDES ET VARIOLIFORMIS ACUTA

The patient presented with an erythematous maculopapular rash on the trunk and extremities. The lesions were occasionally mildly itchy. He had no fever, abdominal pain, arthritis, or other systemic signs or symptoms. He was on amphetamine/dextroamphetamine (Adderall) treatment for attention-deficit disorder, but no other medications. Physical examination revealed a weight of 161 pounds; height, 67.5 inches; blood pressure, 112/70 mm HG; and pulse, 102 beats per minute. Macular and papular lesions were at various stages of development, some scaly with hemorrhagic necrosis. There was no evidence of scarring or ulceration.

A biopsy from a red, minimally scaly patch on the right arm revealed mild thickening of the epidermis (acanthosis) with prominent intercellular edema (spongiosis) and overlying scale (hyperkeratosis). There also was extensive lymphocytic infiltration of the epidermis.

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Vacuolar degeneration of the basal cell layer and a mild red blood cell extravasation were present at the epidermal-dermal junction. A dense, chronic, inflammatory infiltrate cuffed the dermal vessels. Occasional necrotic keratinocytes were noted within the epidermis. The clinical findings and histology were typical of pityriasis lichenoides et varioliformis acuta (PLEVA).

Discussion

Pityriasis lichenoides (PL) is an uncommon inflammatory skin disorder of unknown etiology. First described in 1894 separately by Josef Jadassohn and Albert Neisser, the disorder may be chronic (pityriasis lichenoides chronica [PLC]) or acute PLEVA. The clinical findings are dynamic since some patients with PLEVA may evolve into PL, while others may present initially with chronic skin lesions. 

Little is known about the prevalence, incidence, and risk factors of PLEVA in the general population, but because PLEVA is often delayed or missed altogether, prevalence might be higher than reported.¹ Based on the available literature, there appears to be no racial or geographic predisposition. The condition occurs in all age groups, but it is most often seen in the second or third decade of life. It also occurs in children, predominantly males, with a peak age between 5 and 10 years. It has been described in infants.^1,2  

Pityriasis lichenoides et varioliformis acuta typically presents with crops of 2-mm to 3-mm erythematous macules that quickly develop into papules with fine scales.¹Over several days, these papules rapidly develop into vesiculopustular (sometimes necrotic) and ulcerated papules with red-brown crusting. These lesions occur in several stages of development, and this has been established as an important diagnostic sign.

Lesions will most often occur on the trunk, extremities, and flexural area, but also may be disseminated over the body. Varioliform scars and postinflammatory hyperpigmentation and hypopigmentation may develop as well. In some cases, the lesions may come and go spontaneously for weeks to months and even years.³ Occasionally, symptoms may include pruritus and burning.

Although the clinical picture may suggest the disease, the diagnosis of PLEVA can usually be confirmed by histological assessment of a skin biopsy from the affected area. The typical histopathology of PLEVA shows perivascular, lymphocytic, and histiocytic infiltration of the dermoepidermal junction. In addition, Pautrier-like microabcesses can be seen in clusters of small, atypical, hyperchromatic lymphocytes with larger mononuclear cells.

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Evidence of erythrocyte extravasation, edema, basal vacuolar degeneration, and epidermal necrosis also may be seen. Histologic and clinical findings of PLEVA can overlap with or be mistaken for lymphomatoid papulosis, erythema multiforme, pityriasis rosea, arthropod bite reaction, secondary syphilis, guttate psoriasis, vasculitis, and Gianotti-Crosti syndrome.^1,3             

Although there is no panacea for PLEVA and many patients are not symptomatic, for many practitioners the preferred first line of treatment of PLEVA in children is oral erythromycin.³ Phototherapy using ultraviolet light (UV) also has been found to be an effective treatment of PLEVA, yet the long-term effects of UV light on children are not fully understood. Because of this, psoralen plus UVA (PUVA) and UVB are used as a second-line treatment and also may be used preventatively during remission. For resistant cases associated with severe pain, pruritus, and/or scarring, cyclosporine, dapsone (diaminodiphenyl sulfone), methotrexate, and oral retinoids may be helpful.³Topical corticosteroids may be used to help alleviate pruritus, but these are not effective in treating the actual disease.

It appears that localized cases of PLEVA take significantly longer to resolve than generalized cases. Additionally, children seem to experience a more severe disease when compared with adults and they are less likely to respond to treatment or go into early remission. Moreover, PLEVA may evolve into less inflammatory PLC that can persist for long periods.

There are no known deaths related to PLEVA or malignant transformation in pediatric cases. Yet, because of the rare cases of malignant progression in adults, regular follow-up is advised in patients with a history of PLEVA.²

REFERENCES

1. Bowers S, Warshaw EM. Pityriasis lichenoides and its subtypes. J Am Acad   Dermatol. 2006;55(4):557-572.

2. Lazaridou E, Fotiadou C, Tsorova C, et al. Resistant pityriasis lichenoides et varioliformis acuta in a 3-year-old boy: successful treatment with methotrexate. Int J Dermatol. 2010;49(2):215-217.

3. Fernandes NF, Rozdeba PJ, Schwartz RA, Kihiczak G, Lambert WC. Pityriasis lichenoides et varioliformis acuta: a disease spectrum. Int J Dermatol. 2010;49(3):257-261.

Ms Charron is a pediatric nurse practitioner, Northern Virginia Pediatric Associates, Falls Church, Virginia. Dr Barakat is clinical professor of pediatrics, Georgetown University Medical Center and George Washington University School of Medicine and Health Sciences, Washington, DC. Dr Tabbara is professor of pathology, George Washington University School of Medicine and Health Science, Washington, DC. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. The authors and section editor have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to allow the authors and section editor to focus on key teaching points. Images also may be edited or substituted for teaching purposes.