eMedicine Specialties > Infectious Diseases > Skin and Soft-Tissue Infections

Molluscum Contagiosum

Author: Ashish C Bhatia, MD, FAAD, Assistant Professor of Clinical Dermatology, Department of Dermatology, Northwestern University, Feinberg School of Medicine; Director of Clinical Research, Department of Dermatology and Dermatologic Surgery, River North Dermatology and Dermatologic Surgery, DuPage Medical Group
Coauthor(s): Tracy Campbell, MD, Staff Physician, Department of Dermatology, Rush Medical Center; Seth Forman, MD, Department of Dermatology, Medical College of Virginia; David Rowe, MD, Pathologist, Laboratory Medicine, Martha Jefferson Hospital; Robert Orenstein, DO, Associate Professor, Department of Medicine, Medical College of Virginia, Virginia Commonwealth University; Medical Director, Infectious Disease Clinic, Medical College of Virginia Hospitals; Julia R Nunley, MD, Professor, Program Director, Dermatology Residency, Department of Dermatology, Virginia Commonwealth University Medical Center
Contributor Information and Disclosures

Updated: Apr 1, 2008

Introduction

Background

In 1817, long before the recent increased incidence of molluscum contagiosum (MC), Bateman first described milky fluids that could be expressed from characteristic lesions. Henderson and Paterson, 2 researchers studying molluscum contagiosum independently 25 years later, described the milky fluid to be cellular. Only later did the 2 researchers realize they had discovered the hallmark intracytoplasmic inclusion body, appropriately named the Henderson-Paterson body (molluscum body).

Until the early 20th century, the medical community remained unsure of the etiology of molluscum contagiosum. Certain authorities believed the papules to be enlarged sebaceous glands, while others postulated that a parasitic infestation caused the lesions. A breakthrough in the study of molluscum contagiosum occurred in 1905 when Juliusburg discovered and documented the viral nature of molluscum contagiosum.

Pathophysiology

The molluscum contagiosum virus, which contains linear double-stranded DNA, causes molluscum contagiosum. Restriction endonucleases have elucidated 4 discrete viral subtypes: molluscum contagiosum virus subtypes I, II, III, and IV. All subtypes are classified as members of the Orthopoxvirus genus or as unspecified poxviruses. When human infection occurs, the epidermal keratinocytes are targeted. Viral replication occurs within the cytoplasm of the infected cell, generating the characteristic cytoplasmic inclusion bodies. Histologically, these inclusion bodies are most evident within the stratum granulosum and stratum corneum layers of the epidermis. Hyperproliferation of the epidermis also occurs because of a doubling in the rate of cellular division of the epidermal basal layer.

The molluscum contagiosum virus causes 3 distinct disease patterns in 3 different patient populations: children, immunocompetent adults, and immunocompromised patients (children or adults). Children acquire the molluscum contagiosum virus through either direct skin-to-skin contact or indirect skin contact via fomites such as gymnasium equipment and public baths. Lesions typically occur on the chest, arms, trunk, legs, and face. In adults, molluscum contagiosum is considered a sexually transmitted disease (STD). In almost all cases involving healthy adults, patients exhibit few lesions, which are limited to the perineum, genitalia, lower abdomen, or buttocks. Generally, in immunocompetent populations, molluscum contagiosum is a self-limited disease.

Patients infected with human immunodeficiency virus (HIV) or patients who are otherwise severely immunologically compromised may experience a longer course with more extensive and atypical lesions. In patients infected with HIV, lesions generally are distributed more widely, frequently occur on the face, and may number in the hundreds. The cutaneous manifestations of other opportunistic infections, such as cutaneous cryptococcosis, histoplasmosis, and aspergillosis, may mimic molluscum contagiosum and must be ruled out in immunocompromised hosts.

For additional information on HIV, see Medscape's HIV Transmission & Prevention Resource Center.

Frequency

United States

The incidence of molluscum contagiosum rose from 1960-1980. It is less common than other STDs, occurring in about 1% of the general population. In a 1984 paper published in the Urologic Clinics of North America, Margolis of the Centers for Disease Control and Prevention reportedthat 1 case of molluscum contagiosum occurs for every 42-60 cases of gonorrhea infection.22

The prevalence rate in the population infected with HIV is reported to be 5-18%. In patients who are infected with HIV and who have CD4 cell counts of less than 100 cells/μL, the prevalence of molluscum contagiosum is reported to be as high as 33%.

Mortality/Morbidity

  • Molluscum contagiosum is a self-limited disease in immunocompetent individuals, with no long-term complications or sequelae.
  • In contrast, molluscum contagiosum infection in patients who are infected with HIV may result in conspicuous cosmetic deformities that may have significant adverse psychological effects.
  • Although superinfection and cellulitis have been reported to occur in the setting of molluscum contagiosum in the population infected with HIV, no mortality has been associated directly with the molluscum contagiosum virus.

Race

No racial predilection has been reported.

Sex

The incidence in men reportedly is greater than that in women.

Age

Molluscum contagiosum has been reported in all age groups but is observed most commonly in children and adults who are sexually active. Molluscum contagiosum may occur at any age in immunocompromised patients.

Clinical

History

  • Children  
    • Parents may report recent exposure to other children affected with molluscum contagiosum at school, camp, or public recreational facilities (eg, gymnasiums, swimming pools).
    • Children frequently have active atopic dermatitis.
  • Immunocompetent adults 
    • Affected adults who are otherwise healthy uniformly are sexually active but may not know that their partners are affected.
    • Having multiple sexual partners increases the risk of infection; the frequency of unprotected sex increases the risk of transmission.
  • Patients infected with HIV  
    • Patients generally have low CD4 counts, and the severity of infection is inversely related to the patient's CD4 count.
    • Patients who are poorly compliant or noncompliant with highly active antiretroviral therapy (HAART) for the treatment of HIV are at an increased risk, as are those who have multiple sexual partners.
    • The frequency of unprotected sex also increases the risk of transmission.
  • Miscellaneous  
    • A recent report detailed an eruption of molluscum contagiosum in a patient who had undergone a renal transplant.21
    • Case reports detail molluscum contagiosum eruptions in areas that are treated with tacrolimus 0.1% (Protopic).2,14,42

Physical

Individual lesions are typically discrete, waxy, flesh-colored, dome-shaped, umbilicated papules with a smooth surface. Lesions may be few or numerous, depending on the immunological status of the host. In all patients, lesions generally are asymptomatic, but pruritus and/or perilesional eczematous reactions may develop.

  • In children and healthy adults  
    • Lesions are usually 1-2 mm in diameter and number fewer than 20.
    • In children, lesions generally are distributed on the trunk, arms, legs, and face.
    • In immunocompetent adults, lesions usually are found on the genitalia, lower abdomen, inner upper thighs, and/or buttocks.
    • The average duration of an untreated lesion is 6-9 months but may be as long as 5 years.
  • Individuals who are HIV positive  
    • The disease is generally more severe in patients infected with HIV. Lesions may number in the hundreds and are generally larger (can be >2 cm in diameter) and more deforming and may be confluent.
    • In addition to groin involvement, lesions frequently are found on the face. The duration of untreated lesions may be 5 years or more because molluscum contagiosum may not be self-limiting in this population.
  • In both immunocompetent and immunocompromised individuals, molluscum contagiosum is rarely found in the oral mucosa and conjunctiva.

Causes

Risk factors include the following:

  • Children - Skin-to-skin contact with another affected child or sharing equipment (eg, equipment in a gymnasium)
  • Healthy adults - Primarily sexual contact with an affected partner
  • Immunocompromised patients - Sexual contact with an affected partner, as well as nonsexual skin-to-skin contact with an affected individual
  • Immune suppressant use - Local application of immune suppressants (tacrolimus) may cause a more severe localized eruption.

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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Further Reading

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Keywords

molluscum contagiosum, MC, molluscum contagiosum virus disease, MCV disease, opportunistic infection, sexually transmitted disease, STD, Henderson-Paterson body, Orthopoxvirus genus, renal transplantation, tacrolimus, topical immune suppressants, molluscum body

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Contributor Information and Disclosures

Author

Ashish C Bhatia, MD, FAAD, Assistant Professor of Clinical Dermatology, Department of Dermatology, Northwestern University, Feinberg School of Medicine; Director of Clinical Research, Department of Dermatology and Dermatologic Surgery, River North Dermatology and Dermatologic Surgery, DuPage Medical Group
Ashish C Bhatia, MD, FAAD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Mohs Micrographic Surgery and Cutaneous Oncology, American Medical Association, American Society for Dermatologic Surgery, American Society for Laser Medicine and Surgery, and Connective Tissue Oncology Society
Disclosure: Nothing to disclose.

Coauthor(s)

Tracy Campbell, MD, Staff Physician, Department of Dermatology, Rush Medical Center
Tracy Campbell, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, Chicago Dermatological Society, and Women's Dermatologic Society
Disclosure: Nothing to disclose.

Seth Forman, MD, Department of Dermatology, Medical College of Virginia
Seth Forman, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

David Rowe, MD, Pathologist, Laboratory Medicine, Martha Jefferson Hospital
David Rowe, MD is a member of the following medical societies: United States and Canadian Academy of Pathology
Disclosure: Nothing to disclose.

Robert Orenstein, DO, Associate Professor, Department of Medicine, Medical College of Virginia, Virginia Commonwealth University; Medical Director, Infectious Disease Clinic, Medical College of Virginia Hospitals
Robert Orenstein, DO is a member of the following medical societies: Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Julia R Nunley, MD, Professor, Program Director, Dermatology Residency, Department of Dermatology, Virginia Commonwealth University Medical Center
Julia R Nunley, MD is a member of the following medical societies: American Academy of Dermatology, American College of Physicians, American Society of Nephrology, International Society of Nephrology, Medical Dermatology Society, Medical Society of Virginia, National Kidney Foundation, Phi Beta Kappa, and Women's Dermatologic Society
Disclosure: Johnson and Johnson stock holder dividends; Amgen stock holder dividends; Forest Lab, Inc stock holder dividends; Galaxo Smith Klein stock holder dividends; Covidien stock holder dividends; Novartis Grant/research funds Consulting; Biolex  sub-investigator

Medical Editor

Daniel R Lucey, MD, MPH, Chief, Fellowship Program Director, Department of Internal Medicine, Division of Infectious Diseases, Washington Hospital Center; Professor, Department of Internal Medicine, Uniformed Services University of the Health Sciences
Daniel R Lucey, MD, MPH is a member of the following medical societies: Alpha Omega Alpha and American College of Physicians
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

John W King, MD, Professor of Medicine, Section of Infectious Diseases, Louisiana State University Health Sciences Center; Director, Viral Therapeutics Clinics for Hepatitis; Consulting Staff, Department of Infectious Diseases, Overton Brook Veterans Affairs Medical Center
John W King, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Association of Subspecialty Professors, Infectious Diseases Society of America, and Sigma Xi
Disclosure: emedicine $50.00 author of chapter

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

 
 
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