Molluscum contagiosum

Abstract

Molluscum contagiosum (MC) is a common viral infection of the skin. It presents with universal distribution and is more frequent in children, sexually active adults, and immunodeficient patients. It is caused by the Molluscum contagiosum virus (MCV), a member of the poxviridae family. There are four subtypes of MCV termed MCV-1 to MCV-4, and their variants, however clinically they all appear identical. In children, virtually all infections are caused by MCV-1, whereas in patients infected with HIV, MCV-2 causes the majority of infections. The average incubation time is 2-7 weeks with a range extending to 6 months. The typical lesion of MC is characterised by bright and semi-spherical papules with distinct umbilicated depressions in the centre that contains a greyish plug (the so-called molluscum bodies). Lesions are pink or skin coloured. The size of the papule is variable, usually averaging 2-6 mm, however this depends upon thestage of development. Transmission may occur by direct skin or mucous membrane contact or via contaminated fomites. Autoinoculation and koebnerisation are common and also play a role in the spread of lesions which can be found anywhere on the body. The most common sites affected are the face and neck, followed by trunk and upper extremities. The lesions tend to be disseminated and can become very large (giant molluscum) in immunosupressed patients. Atypical lesions are frequent. Some authors have reported a higher incidence of MC in patients with atopic dermatitis. MC lesions must be differentiated from verruca vulgaris, condyloma accuminata, varicella, herpes simplex, granuloma annulare, folliculitis, cutaneous cryptococcosis, epidermal inclusion cyst, basal cell carcinoma, papular granuloma annulare, keratoacanthoma, lichen planus and syringoma or other adenexal tumors. In immunocompetent, nonatopic patients MC is usually a self-limited disease for which treatment is not mandatory, however when treatment is deemed appropriate, multiple local therapeutic options are available. For patients with impaired immune function and widespread potentially disfiguring eruptions, the usual local destructive therapies are ineffective; antiviral and immunomodulatory medications have been more successful.