AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Background

Molluscum contagiosum is a benign viral disease of the skin that is caused by a member of the poxvirus group, molluscum contagiosum virus (MCV). The virus is one of the largest that causes human disease, measuring 240-320 nm in diameter.

Bateman first described the disease in 1817. The term molluscum was used to describe the pedunculated appearance, and the term contagiosum was used to connote that the disease is transmissible.

Interestingly, the idea of an infectious etiology arose after successful transmission occurred in humans who were inoculated with the materials contained within the lesions. Goodpasture first noted the microscopic similarities that exist between molluscum contagiosum and vaccinia (ie, smallpox).

Pathophysiology

This virus is known to infect only the epidermis. The initial infection seems to occur in the basal layer, and it may be accompanied by a latent period of as long as 6 months. The incubation period is usually shorter (ie, 2-7 wk). This is suggested by the fact that while viral particles are noted in the basal layer, viral DNA replication and the formation of new viral particles do not occur until the spindle and granular layers of the epidermis are involved.

Occasionally, the lesions can progress beyond the local cellular proliferation, and they can become inflamed with the attendant edema, increased vascularity, and infiltration by neutrophils, lymphocytes, and monocytes. Usually, this only occurs if there is a secondary bacterial infection or if rupture into the dermis occurs.

Cell-mediated immunity is thought to be important in modulating and controlling the infection because children and HIV-infected patients are noted to have more widespread and persistent lesions. The incidence and severity of molluscum in HIV-positive and AIDS patients appears to be inversely related to the CD4 count. More severe cases also have been noted in patients who are receiving prednisone and methotrexate. The virus infrequently induces antibody formation; therefore, it is not strongly immunogenic, and reinfection is common.

Frequency

United States

Molluscum contagiosum is a common infection throughout the United States. It accounts for approximately 1% of all diagnoses of skin disorders. The exact incidence in the United States is unknown. Higher incidence in children with eczema as well as in immunocompromised individuals has been documented.

The infection is transmitted by close physical contact, fomites, and autoinoculation (whereby the patient manually spreads the infection from one location to another, by touching or scratching). Crowded living conditions, use of public pools, and sharing of clothes and towels by infected persons have all been implicated in the spread of the virus.

International

Molluscum contagiosum has an incidence of up to 4.5% in some population groups. During a regional outbreak in East Africa, it was estimated that 17% of a village's general population and up to 52% of children older than 2 years developed lesions. Poverty, overcrowding, and poor hygiene play key roles in the propagation of this disease. There appears to be a greater incidence of molluscum in tropical areas, although fairly high incidences have been documented in northern European countries as well.

An Australian study found anti-MCV antibodies in 39% of adults older than 50 years, demonstrating exposure to be very common.

Mortality/Morbidity

Molluscum contagiosum is a benign process; therefore, morbidity and mortality are limited.

• For the most part, morbidity is due to adverse cosmetic results, which usually resolve, without scarring.
• The lesions can undergo secondary bacterial infection, but morbidity is limited when appropriate antibiotics are used.
• Morbidity is greater in immunocompromised and immunodeficient patients since they tend to have a greater number of lesions and more widespread infection, resulting in a greater likelihood of superinfection.
• Despite the rather benign, self-limited course, parents of affected children perceive molluscum to be a significant problem. They cite concerns with scarring, pain, itching, painful treatment, and the chance of spread to peers.

Race

• There is no well-documented predilection for infection among any racial group.
• In one longitudinal study in the United States, 2-4 times as many cases occurred among whites than among other racial groups. This study took place from 1977-1981, and it is unclear if the noted difference was secondary to the differences in accessibility to medical care or other socioeconomic factors.

Sex

Studies do not demonstrate any definite difference in incidence between the sexes.

Age

Infection with molluscum contagiosum occurs in all age groups, and prevalence seems to be increasing.

• The greatest incidence is in children younger than 5 years. This is thought to result from casual contact and autoinoculation.
• Another smaller spike of incidence occurs in young adults, resulting from propagation through sexual contact.
• Infection in infants is rare, perhaps because of the persistence of maternal antibodies.

CLINICAL

Section 3 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

History

• Molluscum contagiosum usually presents as single or multiple (ie, usually no more than 20) discrete, painless, flesh colored papules that classically have a central umbilication.
• • They may spontaneously resolve and are sometimes dismissed by the patient and physician. If very mild, they may not be noticed by the patient.
  • If superinfection already has taken place, the lesions may present as pustules, possibly painful, with erythema and induration.
  • Their diameter usually is 2-6 mm; however, it may be up to 3 cm.
  • The lesions may be tender or pruritic.
  • Beneath the umbilicated center is a white curdlike core.
  • The lesions may be located anywhere, but they have a predilection for the face, trunk, and extremities in children and for the groin and genitalia in adults.
• If children present with genital lesions, sexual abuse should be considered, although autoinoculation is considered the most likely cause of spread to the genitalia in children.
• In general, the disorder is not accompanied by systemic symptoms (eg, fever, nausea, malaise).
• Patients may be able to recall contact with an infected sexual partner, family member, or other person.

Physical

• The physician should note multiple well-defined papules that measure approximately 2-6 mm in diameter.
• Typically, these lesions have a waxy appearance and a central umbilication. They may appear migratory, as individual lesions usually spontaneously resolve over weeks, while new lesions appear elsewhere.
• When the disease appears in an immunocompromised patient, the lesions are more widespread and can be as large as 10-15 mm in diameter.
• If the lesions are superinfected, they show typical signs of bacterial infection (eg, erythema, edema, tenderness, purulence, fever, regional lymphadenopathy).

Causes

• Molluscum contagiosum is a skin disorder that is caused by a DNA virus of the poxvirus group.
• The virus is spread by physical contact with an infected individual or material (fomites, for example shared clothing or towels).
• As many as 25% of the reported cases are from multiple members within a family.

DIFFERENTIALS

Section 4 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

Atypical mycobacterial infections
Basal cell epithelioma/carcinoma
Cryptococcal infection
Disseminated mycosis (HIV)
Keratoacanthoma
Lichen planus
Nevi
Seborrheic dermatitis
Sporotrichosis
Syringoma
Xanthogranulomas
Furunculosis
Warts (verruca vulgaris)
Pyodermas (eg, folliculitis)
Vesicular skin disorders

WORKUP

Section 5 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Lab Studies

• The diagnosis of molluscum contagiosum usually is clinically based upon the appearance and locations of the lesions.
• Staining of thin smears with Giemsa, Gram, or Wright stain should reveal infected cells.

Other Tests

• Molluscum contagiosum viral (MCV) antigens can be detected by fluorescent antibody studies.
• Electron microscopy may identify individual viral particles.

Procedures

• Biopsy
• • Lesions may be biopsied. With hematoxylin and eosin (H&E) staining, the clinician can demonstrate characteristic changes in the epidermis.
  • Biopsy is particularly important in cases where the diagnosis is not clear.

TREATMENT

Section 6 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Emergency Department Care

In general, this disorder requires little, if any, emergency care.

• Benign neglect has been the most common therapy, as individual lesions will usually spontaneously resolve in 2-4 weeks.
• If secondary infection is suspected, then appropriate antistaphylococcal antibiotic coverage should be prescribed.
• Tetanus status should be updated if more than 5-10 years have elapsed since the last booster was given.

Consultations

• The patient should be referred to their primary physician or a dermatologist for treatment. Therapies may include topical vesicants (eg, cantharidin), cryotherapy, curettage, or phototherapy with pulsed dye laser. Cimetidine has been beneficial in atopic patients with MCV infection. Immune-enhancing agents, such as Imiquimod, may stimulate clearance of the virus.
• In the case of widespread lesions or lesions that do not spontaneously resolve, the physician must be mindful of the possibility of HIV infection or other immunocompromised states. In such patients, more urgent consultation with a dermatologist or infectious disease specialist may be warranted. Treatment with systemic or topical antivirals, as well as antiretrovirals, may be beneficial.

MEDICATION

Section 7 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

There have been few well-controlled studies of compounds that may be beneficial in the treatment of molluscum contagiosum.

Since the disease process is self-limiting, invasive or toxic treatments are generally not indicated. More aggressive treatments, such as antivirals, may be required for immunocompromised patients.

For the most part, lesions are treated by destructive, immune-enhancing, or antiviral means. The goal of treatment is to minimize the number of lesions without causing unnecessary scarring.

The mainstay therapy for immunocompetent patients is destruction of the lesions with a variety chemical and physical agents. The treatments of choice at this time are probably cantharidin (a vesicant) and cryotherapy.

Curettage is another treatment option but is more painful and more likely to leave scars. The advantage is that tissue is obtained for diagnostic confirmation.

Other topical treatments reported include salicylic acid and tretinoin gel 0.01%. Silver nitrate, phenol, and trichloroacetic acid have been used, although, again, these are associated with more pain and scarring.

Drug Category: Antihistamines (H2 blockers)

A study of 13 children with molluscum contagiosum, in whom conventional methods of treatment were unsuccessful or difficult to apply, showed improvement with a 2-month course of cimetidine.¹ Of the 13 participants, 12 completed the course of medication, and 9 of the 12 experienced a clearance of all lesions. The remaining 3 showed no new lesions, but some of their lesions were persistent.

This has been reported effective in atopic individuals as well.

Drug Category: Antiviral drugs

Presumably, antiviral drugs may interfere with ability of molluscum contagiosum virus to replicate.

Drug Category: Keratolytic agents

Cause cornified epithelium to swell, soften, macerate, and then desquamate.

Drug Category: Cytotoxic agents

These agents are used to inhibit deregulated cell growth and eliminate viral infected cells.

Drug Name	Salicylic acid and liquid nitrogen
Description	These medications are used to destroy or remove lesions. They are applied topically and often are applied multiple times with intervening debridement of the lesions.
Adult Dose	Apply sparingly to affected area
Pediatric Dose	Apply as in adults
Contraindications	Documented hypersensitivity; diabetes; impaired peripheral circulation; do not use on eyes, mucous membranes, ano-genital or intertriginous areas, moles, birthmarks, or unusual warts with hair; do not use on lesions with other agents or if surrounding tissue is swollen or irritated
Interactions	None reported
Pregnancy	A - Fetal risk not revealed in controlled studies in humans
Precautions	Avoid contact with eyes and mucous membranes; if contact with eyes or mucous membranes occurs, immediately flush with water for 15 min; avoid inhaling the vapors

Drug Category: Retinoids

Vitamin A derivatives have many roles. They encourage cellular differentiation, are antiproliferative, and serve as immunomodulators.

Drug Category: Skin and mucous membrane agents

These agents may have immunomodulatory effects.

FOLLOW-UP

Section 8 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Deterrence/Prevention

• Physical contact with infected individuals should be avoided. Sharing of clothing and towels should be avoided.
• Most of the adolescent and adult cases are secondary to sexual contact. Abstinence and careful selection of sexual partners are important. It is unclear if condoms are effective in preventing the spread of molluscum contagiosum.
• Good personal hygiene is a key factor in avoiding transmission of this disease.

Complications

• Bacterial superinfection
• • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Streptococcus species
• Autoinoculation
• Contagious to others
• Possible extensive infections in immunocompromised individuals

Prognosis

• The prognosis generally is excellent since the disease usually is self-limited.
• In immunocompetent patients, the lesions generally last for 2-4 weeks. The disease usually resolves completely in 2-4 years.
• Recurrences of lesions can occur after the initial clearing in as many as 35% of patients. This is of unknown significance because it may represent reinfection, exacerbation of ongoing disease, or new lesions arising after a prolonged latent period.
• In patients who are infected with HIV or are otherwise immunocompromised, the disease often becomes more generalized, more prolonged, and resistant to treatment. Antiretroviral therapy to restore immune system function has been found to improve MCV infection.

Patient Education

• For infection in children, the physician should stress the benign nature of this ubiquitous disease. However, it can be embarrassing and unsightly for the patient.
• Limiting physical contact with infected individuals and improving personal hygiene should reduce transmission and autoinoculation of the virus.
• Parents should be instructed to watch for possible superinfection (eg, bacterial), which occurs in up to 40% of all cases.
• It is not necessary to keep infected children out of school, although physical contact and sharing of clothes and towels should be discouraged. Sharing of baths should also probably be avoided. Daycare centers may refuse patients with uncovered lesions.
• This disease usually is sexually transmitted in adolescent and adult patient populations, although casual contact may also result in transmission. Safe sex practices and/or abstinence should be discussed, although it is unclear whether condoms and other barrier methods provide adequate protection against the transmission of molluscum contagiosum.
• Patient educators must stress that not all sexually transmitted diseases are as benign as molluscum contagiosum (eg, herpes simplex, gonorrhea, chlamydia, HIV). Abstinence should be practiced until lesions resolve. In patients with multiple sexual partners and/or other risk factors, HIV testing is strongly recommended.
• It is important to note that not all cases in adults are sexually transmitted. Casual skin contact can also result in infection. This diagnosis could cause significant relationship stress.
• For excellent patient education resources, visit eMedicine's Skin, Hair, and Nails Center and Pregnancy and Reproduction Center. Also, see eMedicine's patient education articles Molluscum Contagiosum, Birth Control Overview, and Birth Control FAQs.

MISCELLANEOUS

Section 9 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to consider child abuse in children with genital lesions.
• Failure to consider an undiagnosed immunocompromised state in a patient with extensive disease or in a patient whose condition fails to respond to usual therapy.

ACKNOWLEDGMENTS

Section 10 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Stephen Bretz, MD, to the development and writing of this article.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Media file 1:  Typical molluscum lesions on buttocks. Photo courtesy of F. Fehl III, MD.
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Media type:  Photo

Media file 2:  Molluscum lesions on face and neck. Photo courtesy of F. Fehl III, MD.
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REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

1. Dohil M, Prendiville JS. Treatment of molluscum contagiosum with oral cimetidine: clinical experience in 13 patients. Pediatr Dermatol. 1996;13(4):310-2. [Medline].
2. Meadows KP, Tyring SK, Pavia AT. Resolution of recalcitrant molluscum contagiosum virus lesions in human immunodeficiency virus-infected patients treated with cidofovir. Arch Dermatol. 1997;133(8):987-90. [Medline].
3. Syed TA, Lundin S, Ahmad M. Topical 0.3% and 0.5% podophyllotoxin cream for self-treatment of molluscum contagiosum in males. A placebo-controlled double-blind study. Dermatology. 1994;189(1):65-8. [Medline].
4. Binder B, Weger W, Komericki P, Kopera D. Treatment of molluscum contagiosum with a pulsed dye laser: Pilot study with 19 children. J Dtsch Dermatol Ges. Feb 2008;6(2):121-5. [Medline].
5. Braue A, Ross G, Varigos G. Epidemiology and impact of childhood molluscum contagiosum: a case series and critical review of the literature. Pediatr Dermatol. Jul-Aug 2005;22(4):287-94. [Medline].
6. Brown J, Janniger CK, Schwartz RA. Childhood molluscum contagiosum. Int J Dermatol. Feb 2006;45(2):93-9. [Medline].
7. Dohil MA, Lin P, Lee J. The epidemiology of molluscum contagiosum in children. J Am Acad Dermatol. Jan 2006;54(1):47-54. [Medline].
8. Leslie KS, Dootson G, Sterling JC. Topical salicylic acid gel as a treatment for molluscum contagiosum in children. J Dermatolog Treat. 2005;16(5-6):336-40. [Medline].
9. Luisto M. Unusual and iatrogenic sources of tetanus. Ann Chir Gynaecol. 1993;82(1):25-9. [Medline].
10. Ordoukhanian E, Lane AT. Warts and molluscum contagiosum: Beware of treatments worse than the disease. Postgrad Med. 1997;101(2):223-35. [Medline].
11. Peter G, ed. American Academy of Pediatrics, Molluscum Contagiosum. In: Red Book: Report on the Committee on Infectious Diseases. 24^th ed. 1997:364.
12. Scheinfeld NS. Molluscum Contagiosum. Skinmed. March/April 2008;7(2):89-92. [Medline].

Article Last Updated: Apr 10, 2008