Molluscum contagiosum

Author: Faculty Reviewer: Resident Reviewer:

Publish date: Posted on
Last updated: May 31, 2022

Keywords #

molluscum contagiosum
molluscum
infectious dermatosis

Diagnosis #

Molluscum contagiosum (MC) is a benign skin condition caused by the double-stranded DNA poxvirus, molluscum contagiosum virus (MCV).[1] The condition is most often seen in children but may also arise in immunocompromised individuals or as a sexually transmitted infection. The viral particles are spread via direct skin-to-skin contact or indirect contact with fomites (sharing towels, clothing, toys). After initial inoculation, MC may spread via autoinoculation (i.e. scratching).

Key Concepts #
  • Molluscum contagiosum is a benign skin condition caused by the molluscum contagiosum virus.
  • Most commonly affects children.
  • Spread is via direct (skin to skin) or indirect contact (sharing towels, clothes, toys); further spread occurs via autoinoculation.
  • The disease is generally self-limited, but duration can be variable.
  • Treatment options include cryotherapy, cantharidin application, intralesional candida antigen, and other topical therapies.
Epidemiology #

MC is a common skin condition with an estimated 122 million documented cases in 2010.[1] Most of these cases are seen in children between the age of 2 and 5, but sexually active teenagers and adults, as well as immunocompromised individuals may also be affected. Estimates as high as 18% of individuals living with HIV are affected by MC.[1] There is no gender predominance.

Clinical Features #
  • MC presents with characteristic, flesh-colored, dome-shaped, umbilicated papules typically ranging from 1 to 10 mm in diameter.
  • These papules are often asymptomatic but may be painful or itchy.
  • In atopic individuals, eczema may be aggravated by the molluscum lesions and lead to more rapid spread via autoinoculation (scratching) and impaired skin barrier function.1
  • In children, lesions are most often located on the face, trunk, limbs, and axillary areas. In those infected via sexual transmission, lesions are located on the anogenital area, abdomen, and inner thighs.
  • In immunocompromised persons, mollusca can be much larger, mimicking nonmelanoma skin cancer or other infectious diseases, such as histoplasmosis when diffuse.[1]
  • As lesions start to resolve, an inflammatory reaction may make the area look redder and more inflamed.
Differential Diagnoses #
  • Folliculitis
  • Condyloma acuminatum
  • Verruca vulgaris
  • Epidermoid cyst
  • In immunocompromised individuals the differential is much broader:

  • Keratoacanthoma
  • Basal cell carcinoma
  • Lichen planus
  • Cutaneous fungal disorders (histoplasmosis, cryptococcosis, sporotrichosis)
Diagnostic Workup #

Diagnosis of MC is based on clinical examination and relevant history, including duration of symptoms and known contact with other affected individuals. In cases of difficult diagnosis, dermoscopy may be helpful. Dermoscopy reveals a central white-yellow amorphous area with peripheral branched vessels.[1] Biopsy is rarely indicated.

Treatment #

MC is a self-limited disease, but treatment is often sought for cosmetic reasons or to avoid spread to other individuals. There are three basic treatment approach categories: physical removal, chemical destruction, and systemic medications (immune-modulating or antiviral).[2] Physical removal may be done via cryotherapy with liquid nitrogen or curettage. Chemical treatments for MC include application of podophyllotoxin, cantharidin, salicylic acid, benzoyl peroxide, and tretinoin.[2,3]

References #
  1. Badri, Talel, et al. “Molluscum Contagiosum.”” StatPearls (2019).
  2. Leung, Alexander KC, Benjamin Barankin, and Kam LE Hon. “Molluscum contagiosum: an update.” Recent patents on inflammation & allergy drug discovery 11.1 (2017): 22-31.
  3. Vakharia, Paras P., et al. “Efficacy and safety of topical cantharidin treatment for molluscum contagiosum and warts: a systematic review.” American journal of clinical dermatology 19.6 (2018): 791-803.