eMedicine Specialties > Dermatology > Viral Infections

Molluscum Contagiosum

Author: Catharine Lisa Kauffman, MD, FACP, Georgetown Dermatology and Georgetown Dermpath
Coauthor(s): Carissa N Beatty, MPH, Program Manager, Tobacco Technical Assistance Consortium
Contributor Information and Disclosures

Updated: Sep 1, 2009

Introduction

Background

Descriptions of molluscum contagiosum have been in the medical literature since 1817. In 1905, the viral nature of molluscum contagiosum was discovered by Juliusburg. Molluscum contagiosum is a cutaneous infection caused by a large DNA poxvirus that affects both children and adults. Transmission of molluscum contagiosum has been reported by direct skin contact and has occurred in wrestlers, patients of a surgeon with a hand lesion, and children sharing baths, towels, gymnasium equipment, and benches. Autoinoculation also occurs as evidenced by linear arrays of lesions on infected individuals. Molluscum contagiosum can likely be vertically transmitted, similarly to other viruses such as condyloma acuminatum and human papillomavirus (HPV).

Pathophysiology

The virus that causes molluscum contagiosum replicates in the cytoplasm of epithelial cells producing cytoplasmic inclusions, and it may cause enlargement of infected cells.

Frequency

United States

Reported data for 1966-1983 by the National Disease and Therapeutic Index Survey, which compiles information about patterns of disease in office-based practices in the continental United States, showed an increase in the number of patient visits for molluscum contagiosum.1

Based on National Ambulatory Medical Care Survey (NAMCS) data, an estimated 22 visits per 10,000 persons (95% confidence interval, 16.9–27.1) occurred among the general US population from 2001-2005. A population-based estimate of molluscum contagiosum–associated outpatient visits among American Indian/Alaskan natives from 2001-2005 was 20.15 annual outpatient visits per 10,000 American Indian/Alaskan native persons, with the highest incidence among children under age 15 years.2
 
Molluscum contagiosum is more common in patients who are on steroid therapy or in those who have atopic dermatitis, immunodeficiency, or lymphoproliferative disorders. A molluscum contagiosum infection rate of 8% was seen in one study of 528 HIV-positive patients. The severity of molluscum contagiosum is inversely related to the CD4 T-lymphocyte count. Molluscum contagiosum has been reported in 5.6% of children in kindergarten and in 7.4% of elementary school children.

International

Molluscum contagiosum is common in the tropics and subtropics, probably because of the increased desquamation associated with hydration. Childhood molluscum contagiosum is common in Papua New Guinea, Fiji, and certain parts of Africa. Epidemiological studies suggest that transmission may be related to poor hygiene and climatic factors, such as warmth and humidity.

Race

Persons of any race can be affected by molluscum contagiosum.

Sex

Molluscum contagiosum affects both sexes equally.

Age

Molluscum contagiosum appears to have a bimodal age distribution. The first is in childhood, when transmission occurs from nonsexual skin contact. The second is in early adulthood (age 15-29 y), when molluscum contagiosum occurs as a sexually transmitted disease.

Although molluscum contagiosum can occur in persons of any age, population surveys conducted in Papua New Guinea and Fiji have found that the peak incidence of the disease is among children younger than 5 years, with a prevalence of approximately 25%.

Clinical

History

  • Most patients are asymptomatic; some complain of pruritus, tenderness, and pain.
  • Some develop eczema around lesions (10% in series of 95 and 200 cases).
  • The incubation period ranges from weeks to months (14-50 d). Case studies of vertically transmitted molluscum contagiosum describe a relatively short incubation period, with infections appearing on infants between ages of a few days to 6 weeks following maternal exposure.3
  • If patients have eczema or other diseases altering skin barrier function, molluscum may spread more rapidly in affected areas.

Physical

Physical findings generally are limited to the skin, but cases have reported findings on the eyelids and conjunctiva.

  • Skin - Primary lesion of molluscum contagiosum
    • Firm, smooth, umbilicated papules, usually 2-6 mm in diameter (range 1-15 mm), may be present in groups or may be widely disseminated on the skin and mucosal surfaces.
    • The lesions can be flesh-colored, white, translucent, or even yellow in color.
    • The number of lesions varies from 1-20 up to hundreds in some reports.
    • Some lesions become confluent to form a plaque.
    • Lesions generally are self-limited but can persist for several years.
  • Skin - Distribution of molluscum contagiosum
    • In children, papules are located mainly on the trunk and extremities.
    • In adults, lesions often are located on the lower abdominal wall, inner thighs, pubic area, and genitalia.
    • Although rarely found in the mouth or on the palms and soles, cases of molluscum contagiosum involving the oral mucosa, including the lips, buccal mucosa, hard palate, retromolar pad, and tongue, have been reported.
  • Immunocompromised conditions
    • In some conditions (eg, sarcoidosis, lymphocytic leukemia, congenital immunodeficiency, selective immunoglobulin M deficiency, thymoma, prednisone and methotrexate therapy, AIDS, malignancy, atopic dermatitis), multiple widespread, persistent, and disfiguring lesions can occur, especially on the face and possibly involving the neck and trunk.
    • Patients with AIDS often develop larger (>5 mm) and a greater number of lesions (>30). Lesions larger than 15 mm have been described.


Multiple papules on the face of an HIV-positive m...

Multiple papules on the face of an HIV-positive man.

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Multiple papules on the face of an HIV-positive m...

Multiple papules on the face of an HIV-positive man.

Causes

  • DNA poxvirus, the largest virus known (200 X 300 X 100 nm), causes molluscum contagiosum. The inner and outer membranes of the virion surround a dumbbell-shaped nucleoid. The genome is a linear duplex DNA with an estimated weight of 120-200 megadaltons. Restriction endonuclease analysis of the molluscum contagiosum virus (MCV) reveals 4 viral subtypes named MCV 1, 2, 3, and 4. All subtypes cause similar clinical symptoms. The most common subtypes, MCV 1 and MCV 2, have genomes of 185 kilobases (kb) and 195 kb, respectively.
  • MCV encodes an antioxidant protein (MC066L), selenoprotein, which functions as a scavenger of reactive oxygen metabolites and protects cells from UV or peroxide damage. The particular role of this protein is not known because the attempt to grow MCV in vitro has not been successful.

More on Molluscum Contagiosum

Overview: Molluscum Contagiosum
Differential Diagnoses & Workup: Molluscum Contagiosum
Treatment & Medication: Molluscum Contagiosum
Follow-up: Molluscum Contagiosum
Multimedia: Molluscum Contagiosum
References
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References

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  2. Reynolds MG, Holman RC, Yorita Christensen KL, Cheek JE, Damon IK. The Incidence of Molluscum contagiosum among American Indians and Alaska Natives. PLoS One. 2009;4(4):e5255. [Medline].

  3. Connell CO, Oranje A, Van Gysel D, Silverberg NB. Congenital molluscum contagiosum: report of four cases and review of the literature. Pediatr Dermatol. Sep-Oct 2008;25(5):553-6. [Medline].

  4. van der Wouden JC, Menke J, Gajadin S, et al. Interventions for cutaneous molluscum contagiosum. Cochrane Database Syst Rev. Apr 19 2006;CD004767. [Medline].

  5. Singh OP, Kanwar A. Griseofulvin therapy in molluscum contagiosum. Arch Dermatol. Nov 1977;113(11):1615. [Medline].

  6. Dohil M, Prendiville JS. Treatment of molluscum contagiosum with oral cimetidine: clinical experience in 13 patients. Pediatr Dermatol. Jul-Aug 1996;13(4):310-2. [Medline].

  7. Cathcart S, Coloe J, Morrell DS. Parental satisfaction, efficacy, and adverse events in 54 patients treated with cantharidin for molluscum contagiosum infection. Clin Pediatr (Phila). Mar 2009;48(2):161-5. [Medline].

  8. Myhre PE, Levy ML, Eichenfield LF, Kolb VB, Fielder SL, Meng TC. Pharmacokinetics and safety of imiquimod 5% cream in the treatment of molluscum contagiosum in children. Pediatr Dermatol. Jan-Feb 2008;25(1):88-95. [Medline].

  9. Gold MH, Moiin A. Treatment of verrucae vulgaris and molluscum contagiosum with photodynamic therapy. Dermatol Clin. Jan 2007;25(1):75-80. [Medline].

  10. Betlloch I, Pinazo I, Mestre F, Altes J, Villalonga C. Molluscum contagiosum in human immunodeficiency virus infection: response to zidovudine. Int J Dermatol. Jun 1989;28(5):351-2. [Medline].

  11. Hicks CB, Myers SA, Giner J. Resolution of intractable molluscum contagiosum in a human immunodeficiency virus-infected patient after institution of antiretroviral therapy with ritonavir. Clin Infect Dis. May 1997;24(5):1023-5. [Medline].

  12. Inui S, Asada H, Yoshikawa K. Successful treatment of molluscum contagiosum in the immunosuppressed adult with topical injection of streptococcal preparation OK-432. J Dermatol. Sep 1996;23(9):628-30. [Medline].

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  14. Nelson MR, Chard S, Barton SE. Intralesional interferon for the treatment of recalcitrant molluscum contagiosum in HIV antibody positive individuals--a preliminary report. Int J STD AIDS. Sep-Oct 1995;6(5):351-2. [Medline].

  15. [Guideline] British Association for Sexual Health and HIV (BASHH). Kingdom national guideline on the management of molluscum contagiosum. National Guidelines Clearinghouse. Feb 2008.

  16. [Guideline] University of Texas, School of Nursing, Family Nurse Practitioner Program. Management of molluscum contagiosum. May 2008.

  17. Hanna D, Hatami A, Powell J, et al. A prospective randomized trial comparing the efficacy and adverse effects of four recognized treatments of molluscum contagiosum in children. Pediatr Dermatol. Nov-Dec 2006;23(6):574-9. [Medline].

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Further Reading

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Contributor Information and Disclosures

Author

Catharine Lisa Kauffman, MD, FACP, Georgetown Dermatology and Georgetown Dermpath
Catharine Lisa Kauffman, MD, FACP is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Royal Society of Medicine, Society for Investigative Dermatology, and Women's Dermatologic Society
Disclosure: Nothing to disclose.

Coauthor(s)

Carissa N Beatty, MPH, Program Manager, Tobacco Technical Assistance Consortium
Carissa N Beatty, MPH is a member of the following medical societies: American Public Health Association
Disclosure: Nothing to disclose.

Medical Editor

Mark W Cobb, MD, Consulting Staff, WNC Dermatological Associates
Mark W Cobb, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, and American Society of Dermatopathology
Disclosure: Nothing to disclose.

Pharmacy Editor

David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic
David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Managing Editor

Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine
Edward F Chan, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, and Society for Investigative Dermatology
Disclosure: Nothing to disclose.

CME Editor

Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University
Catherine Quirk, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Dermatology
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

 
 
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