Molluscum Contagiosum

Molluscum Contagiosum

Collin Luk, BHSc, and
Alexander K. C. Leung, MD

University of Calgary

A 13-year-old boy presented with a cluster of pearly white papules on the right side of his back. The child first started noticing these lesions 2 months previously, and he expressed concern that they had increased in number. The lesions were asymptomatic, and the child was otherwise well. Upon closer inspection of the lesions, a diagnosis of molluscum contagiosum was made.

Molluscum contagiosum is caused by the molluscum contagiosum virus, which is a poxvirus of the Poxviridae family.1,2 Typically, molluscum contagiosum presents as discrete, smooth, dome-shaped, waxy papules with central umbilication from which a plug of cheesy material can be expressed.1 The color also can be pearly white, yellow, flesh-colored, translucent, or red (especially when irritated). The lesions most commonly are seen in apposing skin folds or in moist areas such as the antecubital and popliteal fossae, the crural folds, and the torso. Involvement of the palms and soles is characteristically absent. Lesions usually are 1 to 5 mm in diameter, and the number is usually less than 20.1 They often appear in clusters or in a linear pattern. In immunocompromised persons, lesions may occur in atypical locations such as the face and may be of different sizes. The lesions tend to be rapidly progressive, disseminated, refractory to treatment, and frequently recurring.

molluscum

The diagnosis usually is clinical. In cases where a diagnosis is uncertain, a Tzanck smear can be performed on a scraping from a representative lesion.3 Histopathologic examination shows the characteristic large intracytoplasmic eosinophilic inclusion bodies with hematoxylin-eosin staining.2

Epidemiologic data from the United States suggests a childhood prevalence rate of between 2% and 10%, and that molluscum contagiosum accounts for approximately 1% of all diagnosed dermatologic conditions.1,4 However, despite cases having been reported worldwide, there is a greater incidence in areas with topical and humid climates.1,2 Molluscum contagiosum is rare in children under the age of 1 year; elementary school-aged children are more commonly affected.5 This likely can be attributed to the fact that the virus is transmitted by way of person-to-person contact, autoinoculation, and fomites.2

Main complications include cosmetic issues, psychological embarrassment, secondary bacterial infection, conjunctivitis, and superficial punctate keratitis.1 Treatment of molluscum contagiosum includes mechanical, chemical, immune-modulating, and antiviral therapies.1,2,6 However, one systematic review showed that no single intervention was unequivocally effective in the treatment of molluscum contagiosum.6 Some authors suggest benign neglect of the lesions and to await spontaneous resolution. Despite the difference in treatment opinion, it is important to prevent the spread of the infection by educating patients on employing bathtub isolation, avoiding towel sharing, avoiding swimming in pools, and abstaining from participating in contact sports.1 Without active treatment, it is typically considered as a benign and self-limiting disease that resolves spontaneously in 6 to 9 months without residual scarring.7

Our patient was treated with liquid nitrogen, with resolution of the lesions in 4 weeks.

References:

1.Leung AKC, Davies HD. Molluscum contagiosum: an overview. Curr Pediatr Rev. 2012;8(4):346-349.

2.Brown J, Janniger CK, Schwartz RA, Silverberg NB. Childhood molluscum contagiosum. Int J Dermatol. 2006;45(2):93-99.

3.Cotell SL, Roholt NS. Images in clinical medicine: molluscum contagiosum in a patient with the acquired immunodeficiency syndrome. N Engl J Med. 1998;338(13):888.

4.Gottlieb SL, Myskowski PL. Molluscum contagiosum. Int J Dermatol. 1994;33(7):453-461.

5.Braue A, Ross G, Varigos G, Kelly H. Epidemiology and impact of childhood molluscum contagiosum: a case series and critical review of the literature. Pediatr Dermatol. 2005;22(4):287-294.

6.van der Wouden JC, van der Sande R, van Suijlekom-Smit LWA, Berger M, Butler CC, Koning S. Interventions for cutaneous molluscum contagiosum. Cochrane Database Syst Rev. 2009;4:CD004767.

7.Coloe J, Morrell DS. Cantharidin use among pediatric dermatologists in the treatment of molluscum contagiosum. Pediatr Dermatol. 2009;26(4):405-408.

Deepak M. Kamat, MD, PhD—Series Editor:Dr Kamat is professor of pediatrics at Wayne State University in Detroit. He is also director of the Institute of Medical Education and vice chair of education at Children’s Hospital of Michigan, both in Detroit.