An otherwise healthy 4-year-old girl presents with clusters of smooth, pearly, umbilicated papules 2-to-6 mm in diameter. The rash first appeared as groups of waxy, skin-colored papules on the girl’s arm, but soon spread to her torso, axilla, face and eyes and became inflamed and itchy.
The girl is enrolled in swimming lessons at the local public pool and family history is positive for eczema. What’s your diagnosis?
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Molluscum contagiosum virus is a common benign viral disease that mostly affects children and is caused by a poxvirus.
The disease, which is spread person to person and by fomites, can occur at any age, but the vast majority of cases occur in children younger than five who come in contact with MCV on towels, sponges, washcloths and other public areas. In adults and teenagers, MCV is often sexually transmitted, with people with HIV and other immunocompromised patients at particular risk for the disease.
Lesions usually occur in groups and can be located on any are of the skin and mucous membranes, but are more common on the face, trunk and extremities in children and the groin and genitalia in adults.
Although typically painless and discrete, about 10% of patients develop eczema around the papules and children with existing dermatitis may scratch and spread the rash, resulting in a more disseminated presentation. The lesions may become inflamed and discharge pus when pressed. Lesions that develop around the eye can become complicated with conjunctivitis and keratitis.
Other secondary bacterial infections may also occur.Immunocompetent children and adults usually develop less than 20 lesions, but patients with lesions in intertriginous areas can develop hundreds. Additionally, lesions may be larger in patients with HIV/AIDS, sometimes resembling cutaneous tumors.
Clinicians can usually diagnose MCV based on the distinctive clinical appearnce of the lesions, but may also used stained smears of the expressed core and biopsy to differentiate from other similar looking skin conditions including varicella, pyoderma, papillomas, epitheliomas and basal cell carcinoma.
MCV is a self-limited infection and most lesions resolve without treatment within six to nine months, but some can persist or recur for as many as three to four years in immunocompromised patients. Benign neglect is often the best course of action in children with mild cases of MCV, but clinicians may choose to treat patient with more widespread and uncomfortable lesions by removal with liquid nitrogen or a sharp curette. Patients should be informed that more than one treatment is often necessary to minimize treatment failure disappointment.Severe cases may warrant more aggressive treatments with lasers, imiquimod, antiviral therapy, or some combinations of these. There is limited evidence to support the use of treatments including tretinoin, salicylic acid, potassium hydroxide and cantharidin in certain situation. For patients with HIV, effective antiretroviral therapy is likely necessary before lesions resolve. All patients should be educated about prognosis, risk of transmitting the infection to others and autoinoculation, prognosis, therapeutic options and risks of therapy at the first visit.
1. Freedberg IM, Isin AZ, Wolff K, et al. Fitzpatrick’s Dermatology in General Medicine (5th ed.). 1999. New York: McGraw-Hill.
2. Crow MA. “Pediatric molluscum contagiosum.” MedScape Reference.