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A 6-year-old boy with edematous, erythematous papules on arms, legs
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A 6-year-old boy presents to your office with worsening rash. He began developing small skin-colored to pink papules on the right chest approximately 7 months ago. The papules spread to his right arm and abdomen. They are asymptomatic. Approximately 3 weeks ago, his parents noticed he erupted in larger, pruritic papules appearing on the extensor arms and legs. He is otherwise well. His sister had similar, small, skin-colored papules on the arms for several months that resolved last year without treatment.
Physical examination reveals 1-mm to 3-mm skin-colored to pink umbilicated, pearly papules on the chest, arms and abdomen (not pictured). There also are innumerable 3-mm to 8-mm pink to red, edematous, focally crusted papules on the extensor arms and legs, more concentrated at the elbows and knees (Figures 1 and 2).
Carrie C. Coughlin
Marissa J. Perman
Can you spot the rash?
Diagnosis: Gianotti-Crosti syndrome-like reaction in a patient with molluscum contagiosum
Case Discussion
Molluscum contagiosum (MC) is a type of poxvirus that causes a common cutaneous viral infection. It typically presents with small, umbilicated, translucent, pink papules in children with a predilection for the skin folds. The rash is self-limited, although in some patients it takes months or, rarely, years to resolve and may be symptomatic or cosmetically displeasing. Thus, some parents and children desire treatment. Patients can develop inflammatory reactions to the virus de novo or after therapy for molluscum. These reactions include eczematous dermatitis, inflamed, suppurative molluscum lesions, and Gianotti-Crosti syndrome-like reaction (GCLR).
Viral triggers for GCS
Gianotti-Crosti syndrome (GCS) also is known as papular acrodermatitis of childhood. Gianotti described the rash first in 1955, and then reported more cases with Crosti in 1956. It typically develops after a viral infection and has been reported to follow vaccinations, as well. Hepatitis B and Epstein-Barr virus infections are the most often cited viral triggers, but several other viruses have been associated with the exanthem. It classically presents with papules on the cheeks, arms, legs and/or buttocks with notable sparing of the trunk in most cases. The papules are symmetric and primarily on extensor surfaces. The mechanism causing this exanthem is unknown.
Figure 1: Numerous centrally crusted, pink papules concentrated on the knees in Gianotti-Crosti syndrome-like reaction. Figure 2: Right arm showing the predilection for extensor surfaces in Gianotti-Crosti syndrome-like reaction.
Source: Perman MJ
The rash described in this case presentation is deemed “Gianotti-Crosti syndrome like” because it developed in the setting of persistent molluscum and was moderately pruritic. Early it its development (when papules are small), GCLR could be mistaken for an exacerbation of MC; parents might worry this is a sign that topical treatment led to a molluscum flare. Similar to GCS, GCLR occurs mainly on extensor extremities with a predilection for the elbows and knees. The face, buttocks and, less commonly, the trunk also can be involved. Lesions consist of variably sized, moderately pruritic, pink, edematous, centrally crusted papules and papulovesicles.
GCLR is thought to be a cell-mediated immune response and may be associated with clearance of the virus. In a recent review of their institution’s experience with inflammatory reactions to MC, Berger and colleagues noted that their patients with GCLR who had 2-month follow-up data had a significant reduction in the number of their MC lesions in the 2 months after the eruption. The GCLR rash lasted a mean of 6 weeks. The incidence was the same in patients with and without atopic dermatitis.
The differential diagnosis includes classic GCS, papular urticaria or drug hypersensitivity. Papular urticaria should resolve more quickly and generally involves the trunk. The acral predominance and occurrence in patients with MC who would most likely have had topical treatment (if any) would point against drug hypersensitivity. GCLR could mimic scabies, but scabies infection would be more pruritic and could be identified on microscopic examination of a skin scraping.
The exanthem will resolve without any intervention, but moderate potency topical corticosteroids may be used in GCLR, both for clearance and to alleviate pruritus.
Physicians should be aware of this diagnosis to provide reassurance to parents about its benign nature. Moreover, the eruption can herald improvement of MC infection.
References:
Brandt O. J Am Acad Dermatol. 2006;54:136-145.
Retrouvey M. Pediatr Dermatol. 2013;30:137-157.
Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.
Disclosure: Coughlin and Perman report no relevant financial disclosures.