Eczematous molluscum contagiosum masquerading as herpes simplex in an 8-year-old: A case report

Abstract

Molluscum contagiosum is a common pediatric viral skin infection characterized by small, flesh-colored, umbilicated papules on the skin. Molluscum contagiosum lesions are typically benign and self-resolve, but they may trigger a surrounding eczematous dermatitis that may mimic other infections or an atopic dermatitis flare. We report a case of an 8-year-old boy with eczematous molluscum contagiosum whose eruption masqueraded as herpes simplex virus infection. The patient presented with a several week history of pruritic rash with bleeding and crusting, but careful examination revealed conventional umbilicated papules consistent with molluscum contagiosum. The dermatitis was managed with conservative skin care, low-potency corticosteroids, and topical antibiotics (for cracked skin/open sores). This case highlights the importance of recognizing molluscum dermatitis and distinguishing it from herpes simplex virus, atopic dermatitis flare, or bacterial infection to avoid unnecessary investigations or treatments.

Introduction

Molluscum contagiosum (MC) is a common cutaneous viral infection in children, caused by a poxvirus. It classically presents as clusters of small (2–5 mm) dome-shaped, flesh-colored papules with central umbilication. ¹ Lesions are usually asymptomatic and self-limited, often resolving spontaneously within months to a few years. ² In some patients, however, MC can trigger an eczematous inflammatory reaction around the lesions or even at distant sites—a phenomenon known as molluscum dermatitis or an id/hypersensitivity reaction. ³ These changes may obscure the classic appearance of MC and lead to misdiagnosis as eczema or even herpes simplex infection. ⁴ We report a pediatric case of molluscum dermatitis that resembled herpes simplex virus (HSV) infection, and we discuss its differential diagnosis and management.

Case report

An 8-year-old boy from Aupaluk, Quebec, who was previously healthy, presented with a 2-month history of a pruritic, bleeding rash on his right underarm, chest, back (crossing midline, Figure 1(a, arrows)), and antecubital fossa (Figure 1). There was no fever, pain, or systemic ailments.

Figure 1.

(a–d) Numerous clustered, dome-shaped, flesh-colored papules measuring 2–3 mm with central umbilication are seen on a background of erythematous and excoriated eczematous plaques. Crusting is present over the axillary lesions due to scratching and secondary irritation. The dermatitis partially obscures the typical central umbilication of many papules, highlighting diagnostic challenge. The spread of lesions beyond flexural areas emphasizes autoinoculation likely exacerbated by scratching. The eruption crosses the midline on the back (arrows).

Prior to referral, a local health care provider in a clinic had prescribed topical tretinoin 0.01% (Stieva-A) to apply to the lesions. After several weeks of tretinoin therapy with no improvement, the patient was brought for further evaluation.

Skin examination revealed numerous 2–3 mm flesh-colored papules with central umbilication clustered on patches of erythematous eczematous skin in the right axilla, right lateral chest, and right antecubital fossa. Some lesions had small crusts from scratching, but no papules/vesicles/pustules were present. The eruption was confined mostly to the right side on the chest but crossed the midline on the back (Figure 1(a, arrows)). No significant lymphadenopathy was noted, and the rest of the examination was unremarkable.

The clinical presentation was consistent with eczematized MC. Dozens of MC papules were present, but their appearance was partially camouflaged by the eczematous reaction and trauma/excoriations. Importantly, the clustered umbilicated papules distinguished the condition from a primary herpes infection. A diagnosis of molluscum dermatitis (MC with an id reaction) was made. The patient’s parents were counseled regarding the benign nature of MC and the likelihood of spontaneous resolution over time.

Management was aimed at the dermatitis. Desonide 0.05% cream was applied twice daily to inflamed areas for inflammation and itch relief, and topical mupirocin 2% was applied to cracked/traumatized lesions. Gentle skin care (moisturizers and avoidance of scratching) was advised. No destructive procedures were performed on the molluscum considering the extent of the disease. The parents were counseled that appearance of dermatitis likely serves a harbinger for future clearance of the virus by the immune system.

Discussion

This case illustrates a common complication of MC: an eczematous or id reaction that can mimic other skin infections. About 10% of children with MC develop eczematous dermatitis. ⁵ This immune response often heralds molluscum resolution. ⁶ Clinically, molluscum dermatitis appears as red, scaly, itchy patches surrounding the MC papules (sometimes even at sites distant from the primary lesions), which can mask umbilicated papules and confuse diagnosis. ³

Key differentials were considered. HSV infection was a primary concern because clustered, eroded papules on an erythematous base could suggest eczema herpeticum. Eczema herpeticum often manifests with grouped vesicles and systemic symptoms—absent in our case. Impetigo was also considered; however, impetigo classically presents with multiple honey-colored crusted erosions and tends to spread quickly, which was not the case here. The crusting on our patient’s lesions was scant and attributable to scratching, and the chronic 2-month course without progression made active bacterial infection unlikely. Finally, an atopic dermatitis flare was considered, but the absence of prior eczema history and evident molluscum papules made this less likely.

Recognition of molluscum dermatitis has important therapeutic implications. Treating the dermatitis can provide symptomatic relief and potentially limit further spread of molluscum via scratching. ⁷ First-line management involves optimizing skin care with moisturizers and using low-potency topical steroids to calm the inflammation. ³ Overuse of strong steroids or immunomodulators may suppress the local immune response and prolong the infection.^8,9 Because the eczematous reaction often indicates that the host is clearing the virus, some recommend emollients alone in mild cases. ⁵ In practice, if the eczema is causing significant discomfort, a short course of a low-potency topical corticosteroid can be used for relief.

Another consideration is secondary bacterial infection. Eczematous skin is prone to superficial infection (e.g. with Staphylococcus aureus). It is worth noting that the oozing and crusting in molluscum dermatitis is usually a sterile inflammatory reaction, not a true infection. ⁶ Systemic antibiotic therapy should be reserved for cases with clear evidence of secondary bacterial infection. In our patient, topical mupirocin sufficed for minor erosions/cracks, and no systemic antibiotics were needed.

Overall, this case underscores that molluscum with an id reaction can mimic HSV or impetigo, potentially leading to misdiagnosis. Awareness of the entity of molluscum dermatitis is crucial. Clinicians should maintain a high index of suspicion for MC in children with atypical eczematous rashes, as prompt recognition can prevent misdiagnosis and unnecessary interventions. Management should support the skin barrier and control symptoms as infection runs its course. With supportive care, molluscum lesions in immunocompetent children resolve spontaneously.