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Dermatology > VIRAL INFECTIONS
Molluscum Contagiosum
Article Last Updated: May 31, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: C Lisa Kauffman, MD, FACP, Professor, Chief, Division of Dermatology, Departments of Medicine and Pathology, Georgetown University Medical Center
C Lisa Kauffman 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 Dermatological Society
Coauthor(s):
Carissa N Beatty, BA, Dermatopathology Coordinator, Georgetown University Hospital;
Sung W Yoon, MD, Fellow, Department of Plastic Surgery, Mayo Clinic at Scottsdale
Editors: Mark W Cobb, MD, Consulting Staff, WNC Dermatological Associates; David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Director, Division of Dermatology, Scott and White Clinic; Director Dermatology Residency Training Program, Scott and White Clinic; Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Author and Editor Disclosure
Synonyms and related keywords:
DNA poxvirus, MCV, molluscum contagiosum virus, MCV 1, MCV 2, selenoprotein, umbilicated papules, cryotherapy with liquid nitrogen, electrodesiccation
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. It is a cutaneous infection caused by a large DNA poxvirus that affects both children and adults. Transmission 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.
Pathophysiology
The virus replicates in the cytoplasm of epithelial cells producing cytoplasmic inclusions, and it may cause enlargement of infected cells.
Frequency
United States
Reported data for 1969-1983 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.
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.
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%.
History
- Most patients are asymptomatic; some complain of pruritus, tenderness, and pain.
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- Some develop eczema around lesions (10% in series of 95 and 200 cases).
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- The incubation period ranges from weeks to months (14-50 d).
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- If patients have eczema or other diseases altering skin barrier function, molluscum may spread more rapidly in affected areas.
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Physical
Physical findings generally are limited to the skin, but cases have reported findings on the eyelids and conjunctiva.
- Skin - Primary lesion
- 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
- In children, papules 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.
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.
Basal Cell Carcinoma
Dermatitis Herpetiformis
Fibrous Papule of the Face
Juvenile Xanthogranuloma (Nevoxanthoendothelioma)
Keratoacanthoma
Lichen Planus
Milia
Spitz Nevus
Warts, Nongenital
Other Problems to be Considered
Histiocytoma
Nevus (intradermal)
Varicella When multiple lesions are present, vulvar syringoma and condyloma acuminata should be considered. In patients with AIDS, cutaneous Cryptococcus infection manifesting as a molluscumlike eruption has been reported.
Lab Studies
- Diagnosis: Generally, diagnosis is made on clinical grounds based on appearance of the lesions. Identification of characteristic intracytoplasmic inclusion bodies in histologic or cytologic preparations is made by hematoxylin and eosin (H&E) staining of biopsy sections.
- Laboratory tests: Serum antibodies have been measured by complement fixation, tissue culture neutralization, fluorescent antibody, and gel agar diffusion techniques; however, they are not well standardized.
- Smears from scrapings of lesions stained by Papanicolaou or Wright, Giemsa, or Gram stains reveal inclusion bodies.
- Antigen of MCV may be identified by fluorescent antibody technique.
Other Tests
- Electron micrographs of fixed material from papule are taken.
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- Sexually active patients also may have other concomitant venereal diseases such as syphilis and gonorrhea, so their partners also should be examined to prevent reinoculation.
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Procedures
- Biopsy is performed if diagnosis is uncertain.
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Histologic Findings
- The epidermis is acanthotic and may measure up to 6 times the normal thickness.
- Basal cells are slightly larger and more columnar than normal, with dense and granular nuclei.
- Above the basal keratinocytes are enlarged keratinocytes with a deep purple appearance.
- The molluscum body is the result of a virally induced cytoplasmic transformation that begins in the lower cells of the epidermis, just above the basal cell layer.
- Keratinocytes contain multiple Feulgen-positive intracytoplasmic inclusion bodies (Henderson-Patterson or molluscum bodies) containing viral particles that can be identified in the cells of stratum spinosum.
- The viral particles increase in size as they progress up toward the granular layer causing compression of the nucleus to the periphery of the infected keratinocytes.
- The core of the down-growth of the central stratum corneum of the papules is largely replaced by viral particles.
- The dermis under the infected lobule of epidermis is normal except for occasional inflammation.
- Approximately 17% of molluscum contagiosum lesions may have an inflammatory reaction.
- In HIV-infected patients, acanthosis, hyperkeratosis, and nuclear atypia are also present. In these patients, viral structures may be present up to 1 cm away from clinically observed lesions.
Medical Care
Molluscum contagiosum generally is self-limited and heals after several months or years. Any one lesion is present for about 2 months; however, to prevent autoinoculation or transmission to close contacts, therapy may be beneficial. The common goal of the different treatment methods is the destruction of the lesions. Controlled studies have not been completed with the various treatments. Commonly used treatments are not approved by the Food and Drug Administration (FDA). - Topical applications
- Cantharidin - A single application that may need to be repeated once or twice every 3-4 weeks
- Tretinoin cream (0.1%) or gel (0.025%) - Applied daily
- Imiquimod cream 5% - Applied under occlusion
- Podophyllin
- Trichloroacetic acid
- Tincture of iodine
- Silver nitrate or phenol
- Cryotherapy with liquid nitrogen - One of the popular treatment modalities
- Systemic agents
- Griseofulvin (single case, anecdotal evidence)
- Methisazone (1methylisatin 2-thiosemicarbazone)
- Cimetidine
- In immunocompromised patients, the treatment success rate increases drastically with the use of antiviral medications, particularly HIV-1 protease inhibitors in combination with nucleoside analogs that inhibit reverse transcriptase. Improvement of lesions was seen in individual cases with the use of ritonavir, cidofovir (intravenous and topical), zidovudine, intralesional interferon alfa, and topical injections of streptococcal antigen OK-432.
Surgical Care
Curettage followed by either light electrodesiccation or the application of a caustic agent to cauterize bleeding points has been shown to be an effective treatment in children and adults. The topical anesthetic cream EMLA (eutectic mixture of local anesthetics) can be applied under occlusion an hour before curettage to decrease the discomfort associated with the procedure.
Activity
Because molluscum contagiosum is known to spread by direct contact and fomites, patients need to be educated regarding transmission of the disease.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
In immunocompromised patients, improvement of lesions was seen in individual cases with the use of ritonavir, cidofovir (intravenous and topical), AZT, intralesional interferon alpha, and topical injections of streptococcal antigen OK-432.
Drug Category: Cauterizing agents
Cause cornified epithelium to swell, soften, macerate, and then desquamate.
| Drug Name | Cantharidin (Verr-Canth) |
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| Description | Effectiveness against warts may result from exfoliation. Lytic action does not affect basal layer and has minimal effect on the corium. Scarring does not occur. |
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| Adult Dose | Single application repeated once or twice q3-4wk |
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| Pediatric Dose | Administer as in adults |
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| Contraindications | Documented hypersensitivity; diabetes; impaired peripheral circulation; do not use on eyes, mucous membranes, anogenital 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 |
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| Interactions | None reported |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Strong vesicant to be used sparingly |
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| Drug Name | Trichloroacetic acid (Tri-Chlor) |
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| Description | Cauterizes skin, keratin, and other tissues. Although caustic, causes less local irritation and systemic toxicity than others in the same class. However, response is often incomplete and recurrence occurs frequently. |
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| Adult Dose | Paint onto lesions, avoid uninvolved skin; can be used in anal areas; repeat q1-2wk |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity; not for use on premalignant or malignant lesions; may cause hyperpigmentation or hypopigmentation |
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| Interactions | None reported |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | External use only; restrict use to treatment areas only |
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| Drug Name | Silver nitrate |
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| Description | Coagulates cellular protein and remove granulation tissue. |
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| Adult Dose | Apply to affected area or lesion for approximately 5 d |
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| Pediatric Dose | Administer as in adults |
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| Contraindications | Documented hypersensitivity; broken skin or cuts |
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| Interactions | Decreases effects of sulfacetamide preparations |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Not for internal use |
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| Drug Name | Tincture of iodine |
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| Description | Cauterizes skin, keratin, and other tissues. Causes less local irritation than others in the same class. |
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| Adult Dose | Apply to affected area |
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| Pediatric Dose | Administer as in adults |
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| Contraindications | Documented hypersensitivity |
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| Interactions | None reported |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Not for application to open skin because it may be absorbed systemically |
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Drug Category: Retinoids
Regulate cell growth and proliferation.
| Drug Name | Tretinoin (Avita, Retin-A) |
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| Description | Inhibits microcomedo formation and eliminates lesions present. Makes keratinocytes in sebaceous follicles less adherent and easier to remove. |
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| Adult Dose | Begin with lowest tretinoin formulation and increase as tolerated; apply hs or qod; lower frequency of application if irritation develops |
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| Pediatric Dose | <12 years: Not established
>12 years: Administer as in adults |
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| Contraindications | Documented hypersensitivity |
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| Interactions | Toxicity increases with coadministration of benzoyl peroxide, salicylic acid, and resorcinol; avoid topical sulfur, resorcinol, salicylic acid, other keratolytics, abrasives, astringents, spices, and lime |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Photosensitivity may occur with excessive sunlight exposure; caution in eczema; do not apply to mucous membranes, mouth, and angles of nose |
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Drug Category: Histamine H2 antagonists
May improve symptoms when coadministered with other treatment modalities.
| Drug Name | Cimetidine (Tagamet) |
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| Description | Histamine H2 receptor agonist. Treats itching, flushing, pruritus, urticaria, and contact dermatitis. |
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| Adult Dose | 300-800 mg PO q6-8h; not to exceed 2400 mg/d |
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| Pediatric Dose | 25-30 mg/kg/d PO divided q4h |
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| Contraindications | Documented hypersensitivity |
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| Interactions | Can increase blood levels of theophylline, warfarin, tricyclic antidepressants, triamterene, phenytoin, quinidine, propranolol, metronidazole, procainamide, and lidocaine |
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| Pregnancy | B - Usually safe but benefits must outweigh the risks.
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| Precautions | Elderly persons may experience confusional states; may cause impotence and gynecomastia in young males; may increase levels of many drugs; adjust dose or discontinue treatment if changes in renal function occur |
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Drug Category: Immune response modifiers
| Drug Name | Imiquimod (Aldara) |
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| Description | Induces secretion of cytokines, including interferon-alpha, TNF, and interleukins; increases T-cell activity. Minimal immediate antiviral activity. May be more effective in women than in men. Use 5% cream. |
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| Adult Dose | Apply 3 times/wk; not to exceed 16 wk; leave on skin 6-10 h |
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| Pediatric Dose | Administer as in adults |
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| Contraindications | Documented hypersensitivity; avoid natural and artificial sun exposure |
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| Interactions | None reported |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Caution with inflamed skin at site; avoid natural and artificial sun exposure; regarding genital use, not recommended for treatment of rectal, cervical, intravaginal, urethral, and intra-anal human papilloma virus infection; following surgery or drug treatment, do not use until genital/perianal tissue is healed |
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Deterrence/Prevention
- Patients should avoid scratching to prevent autoinoculation.
- Patients should avoid sharing of grooming implements (eg, razors, bath towels) and contact with other fomites.
Complications
- Complications include irritation, inflammation, and secondary infections. Lesions on eyelids may be associated with follicular or papillary conjunctivitis.
Prognosis
- Molluscum contagiosum is a benign, self-limited disease.
- Treatments are effective if patients are compliant.
- Additional duration of therapy may be required in immunocompromised patients.
- Overall, prognosis is excellent.
Patient Education
- Since the disease is spread by direct contact, patients should be educated to avoid skin-to-skin contact with others to prevent transmission.
- For excellent patient education resources, visit eMedicine's Skin, Hair, and Nails Center. Also, see eMedicine's patient education article Molluscum Contagiosum.
Special Concerns
- Child abuse: This condition does not suggest child abuse unless other clues are present.
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| Media file 1:
Multiple papules on the face of an HIV-positive man. |
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| Media file 2:
Cytoplasmic viral inclusions become progressively larger toward the epidermal surface (hematoxylin and eosin, 200X) |
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| Media file 3:
Low-power histopathologic examination reveals an overall cup-shaped appearance. |
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| Media file 4:
Viral particles have a dumbbell-shaped appearance. Courtesy of Alvin Zelickson, MD. |
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Molluscum Contagiosum excerpt Article Last Updated: May 31, 2007
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