Molluscum contagiosum

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Molluscum contagiosum
Classification and external resources
Molluscaklein.jpg
Typical flesh-colored, dome-shaped and pearly lesions
ICD-10 B08.1
ICD-9 078.0
DiseasesDB 8337
MedlinePlus 000826
eMedicine derm/270
MeSH D008976

Molluscum contagiosum (MC) is a viral infection of the skin or occasionally of the mucous membranes, sometimes called water warts. It is caused by a DNA poxvirus called the molluscum contagiosum virus (MCV). MCV has no nonhuman-animal reservoir (infecting only humans). There are four types of MCV, MCV-1 to -4; MCV-1 is the most prevalent and MCV-2 is seen usually in adults. The virus that causes molluscum is spread from person to person by touching the affected skin. The virus may also be spread by touching a surface with the virus on it, such as a towel, clothing, or toys. Once someone has the virus, the bumps can spread to other parts of their body by touching or scratching a bump and then touching another part of the body. Molluscum can be spread from one person to another by sexual contact. This common viral disease has a higher incidence in children, sexually active adults, and those who are immunodeficient,[1] and the infection is most common in children aged one to ten years old.[2] MC can affect any area of the skin but is most common on the trunk of the body, arms, groin, and legs. There is evidence that molluscum infections have globally been on the rise since 1966, but these infections are not routinely monitored because they are seldom serious and routinely disappear without treatment. Molluscum contagiosum is contagious until the bumps are gone. Some growths may remain for up to 4 years if not treated.[3]

Signs and symptoms[edit]

Molluscum lesions on an arm.

Molluscum contagiosum lesions are flesh-colored, dome-shaped, and pearly in appearance. They are often 1–5 millimeters in diameter, with a dimpled center.[4] They are generally not painful, but they may itch or become irritated. Picking or scratching the bumps may lead to further infection or scarring. In about 10% of the cases, eczema develops around the lesions. They may occasionally be complicated by secondary bacterial infections. The viral infection is limited to a localized area on the topmost layer of the epidermis.[5] Once the virus-containing head of the lesion has been destroyed, the infection is gone. The central waxy core contains the virus. In a process called autoinoculation, the virus may spread to neighboring skin areas. Children are particularly susceptible to autoinoculation, and may have widespread clusters of lesions.

Individual molluscum lesions may go away on their own and are reported as lasting generally from 6 weeks,[6] to 3 months.[7] The lesions may propagate via autoinoculation so an outbreak generally lasts longer. Mean durations for an outbreak are variously reported from 8 months[6] to about 18 months,[8][9] but durations are reported as widely as 6 months to 5 years, lasting longer in immunosuppressed individuals.[7][9]

Diagnosis[edit]

Molluscum contagiosum virus
Molluscum contagiousum virus.jpg
EM of Molluscum contagiosum virus
Virus classification
Group: Group I (dsDNA)
Family: Poxviridae
Genus: Molluscipoxvirus
Species: Molluscum contagiosum virus
Low magnification micrograph of molluscum contagiosum. H&E stain.
High magnification micrograph of molluscum contagiosum, showing the characteristic molluscum bodies. H&E stain.

Diagnosis is made on the clinical appearance; the virus cannot routinely be cultured. The diagnosis can be confirmed by excisional biopsy.

Histologically, molluscum contagiosum is characterized by molluscume bodies in the epidermis above the stratum basale, which consist of large cells with:

  • abundant granular eosinophilic cytoplasm (accumulated virions), and
  • a small peripheral nucleus.

Treatments[edit]

Treatment options can often involve discomfort to the child so initial recommendations are often expectant management, simply waiting for the lesions to resolve spontaneously.[10] Current treatment options are invasive, requiring tissue destruction and attendant discomfort. Currently there is no US licensed molluscum contagiosum vaccine; attempts have been made but it is difficult to instill a permanent immunity to the virus.

Treatments causing the skin on or near the lesions to rupture may spread the infection further, much the same as scratching does.[11]

Bumps located in the genital area may be treated in an effort to prevent them from spreading.[9] When treatment has resulted in elimination of all bumps, the infection has been effectively cured and will not reappear unless the person is reinfected.[12]

Medications[edit]

Astringent chemicals applied to the surface of molluscum lesions to destroy successive layers of the skin include potassium hydrochloride, and cantharidin.[13]

Two randomized, placebo controlled clinical trials treating molluscum in children with a combination of essential oils have demonstrated the effectiveness in children with molluscum. The second, more recent study showed a 90% or greater reduction in the number of visible molluscum lesions in 16 of 19 children (84.2%) using a combination of essential oil of Melaleuca alternifolia (tea tree oil) and organically bound iodine [14] . Tea tree oil alone worked for only 18% of children.

Thirty-one children (mean age 4.6 +/- 2.1 years) with the diagnosis of molluscum contagiosum (mean length of time with condition 8.6 +/- 5.3 months) were treated with once daily topical application of a 10% solution (v/v) of essential oil of Australian lemon myrtle (Backhousia citriodora) or vehicle (olive oil). At the end of 21 days, there was greater than 90% reduction in the number of lesions in 9/16 children treated with lemon myrtle oil, while 0/16 children met the same criteria for improvement in the vehicle group (P < 0.05). No adverse events were reported.[15]

For mild cases, over-the-counter wart medicines, such as salicylic acid may or may not[16] shorten infection duration. Daily topical application of tretinoin cream may also trigger resolution.[17][18] These treatments require several months for the infection to clear, and are often associated with intense inflammation and possibly discomfort.

Imiquimod, a form of immunotherapy, had been proposed as a treatment for molluscum, based on promising results in small case series and clinical trials.[19][20] However, two large randomized controlled trials, specifically requested by the U.S. Food and Drug Administration under the Best Pharmaceuticals for Children Act[21] and completed in 2006, both demonstrated that imiquimod cream, applied three times per week, was after 18 weeks no more effective than placebo cream in treating molluscum in a total of 702 children aged 2–12 years old.[22] In 2007[23] results from those trials—which have not been published in the medical literature or incorporated into the medical literature[24]—were incorporated into FDA-approved prescribing information for imiquimod, which states: "Limitations of Use: Efficacy was not demonstrated for molluscum contagiosum in children aged 2–12."[22] Imiquimod's FDA-approved prescribing information in 2007 was also updated to document concerning safety issues raised in the two large randomized controlled trials as well as a smaller pharmacokinetic study (also requested by FDA and subsequently published[25]), including:

  • Potential adverse effects of imiquimod use: "Similar to the studies conducted in adults, the most frequently reported adverse reaction from 2 studies in children with molluscum contagiosum was application site reaction. Adverse events which occurred more frequently in Aldara-treated subjects compared with vehicle-treated subjects generally resembled those seen in studies in indications approved for adults and also included otitis media (5% Aldara vs. 3% vehicle) and conjunctivitis (3% Aldara vs. 2% vehicle). Erythema was the most frequently reported local skin reaction. Severe local skin reactions reported by Aldara-treated subjects in the pediatric studies included erythema (28%), edema (8%), scabbing/crusting (5%), flaking/scaling (5%), erosion (2%) and weeping/exudate (2%)."[22]
  • Potential systemic absorption of imiquimod, with negative effects on white blood cell counts overall, and specifically neutrophil counts: "Among the 20 subjects with evaluable laboratory assessments, the median WBC count decreased by 1.4*109/L and the median absolute neutrophil count decreased by 1.42×109 L−1."[22]

There is no high quality evidence for cimetidine.[26]

Surgery[edit]

Surgical treatments include cryosurgery, in which liquid nitrogen is used to freeze and destroy lesions, as well as scraping them off with a curette. Application of liquid nitrogen may cause burning or stinging at the treated site, which may persist for a few minutes after the treatment. Scarring or loss of color can complicate both these treatments. With liquid nitrogen, a blister may form at the treatment site, but it will slough off in two to four weeks. Although its use is banned by the FDA in the United States in its pure, undiluted form, the topical blistering agent cantharidin can be effective.[27] Cryosurgery and curette scraping are not painless procedures. They may also leave scars and/or permanent white (depigmented) marks.

Laser[edit]

Pulsed dye laser therapy may be used for cases that are persistent and do not resolve following other measures.[28] As of 2009 however there is no evidence for genital lesions.[29]

Prognosis[edit]

Most cases of molluscum will clear up naturally within two years (usually within nine months). So long as the skin growths are present, there is a possibility of transmitting the infection to another person. When the growths are gone, the possibility for spreading the infection is ended.[12]

Unlike herpes viruses, which can remain inactive in the body for months or years before reappearing, molluscum contagiosum does not remain in the body when the growths are gone from the skin and will not reappear on their own.[12] However, there is no permanent immunity to the virus, and it is possible to become infected again upon exposure to an infected person.

One advantage of treatment is to hasten the resolution of the virus. This limits the size of the "pox" scar. If left untreated, molluscum growth can reach sizes as large as a pea or a marble. Spontaneous resolution of large lesions can occur, but will leave a larger, crater-like growth. As many treatment options are available, prognosis for minimal scarring is best if treatment is initiated while lesions are small.

Epidemiology[edit]

Approximately 122 million people were affected worldwide by molluscum contagiosum as of 2010 (1.8% of the population).[30]

See also[edit]

References[edit]

  1. ^ Hanson D, Diven DG (March 2003). "Molluscum contagiosum". Dermatol. Online J. 9 (2): 2. PMID 12639455. 
  2. ^ "Frequently Asked Questions: For Everyone. CDC Molluscum Contagiosum". United States Centers for Disease Control and Prevention. Retrieved 2008-06-29. 
  3. ^ "Molluscum (Molluscum Contagiosum) FAQ". Centers for Disease Control and Prevention. Retrieved 26 December 2013. 
  4. ^ Likness, LP (June 2011). "Common dermatologic infections in athletes and return-to-play guidelines.". The Journal of the American Osteopathic Association 111 (6): 373–379. PMID 21771922. 
  5. ^ "Pamphlets: Molluscum Contagiosum". American Academy of Dermatology. 2006. Retrieved 2008-11-30. 
  6. ^ a b Weller R, O'Callaghan CJ, MacSween RM, White MI (1999). "Scarring in molluscum contagiosum: comparison of physical expression and phenol ablation". BMJ 319 (7224): 1540. doi:10.1136/bmj.319.7224.1540. PMC 28297. PMID 10591712. 
  7. ^ a b Molluscum Contagiosum at eMedicine
  8. ^ MedlinePlus Encyclopedia Molluscum Contagiosum
  9. ^ a b c Tyring SK (2003). "Molluscum contagiosum: the importance of early diagnosis and treatment". Am. J. Obstet. Gynecol. 189 (3 Suppl): S12–6. doi:10.1067/S0002-9378(03)00793-2. PMID 14532898. 
  10. ^ Prodigy knowledgebase (July 2003). "Molluscum Contagiosum". National Health Service. Retrieved 2010-04-20. —UK NHS guidelines on Molluscum Contagiosum
  11. ^ van der Wouden JC, Menke J, Gajadin S, et al. (2006). "Interventions for cutaneous molluscum contagiosum". In Van Der Wouden, Johannes C. Cochrane Database Syst Rev (2): CD004767. doi:10.1002/14651858.CD004767.pub2. PMID 16625612. 
  12. ^ a b c "Frequently Asked Questions: For Everyone. CDC Molluscum Contagiosum". United States Centers for Disease Control and Prevention. Retrieved 2008-12-08. 
  13. ^ "Molluscum Contagiosum - Treatment Overview". WebMD. January 12, 2007. Retrieved 2007-10-21. 
  14. ^ Markum E, Baillie J (2012). "Combination of essential oil of Melaleuca alternifolia and iodine in the treatment of molluscum contagiosum in children". J Drugs Dermatol.v 11 (3): 349–54. PMID 22395586. 
  15. ^ http://www.ncbi.nlm.nih.gov/pubmed/15183850
  16. ^ Schmitt, Jochen; Diepgen, Thomas L. (2008). "Molluscum contagiosum" (PDF). In Berthold Rzany; Williams, Hywel; Bigby, Michael E.; Diepgen, Thomas L.; Herxheimer, Andrew; Luigi Naldi. Evidence-Based Dermatology. Evidence-based Medicine. London: BMJ Books. ISBN 1-4051-4518-8. 
  17. ^ Papa C, Berger R (1976). "Venereal herpes-like molluscum contagiosum: treatment with tretinoin". Cutis 18 (4): 537–40. PMID 1037097. 
  18. ^ Credo, BV; Dyment, PG (1996). "Molluscum Contagiosum". Adolesc Med 7 (1): 57–62. PMID 10359957. 
  19. ^ Hanna D, Hatami A, Powell J, et al. (2006). "A prospective randomized trial comparing the efficacy and adverse effects of four recognized treatments of molluscum contagiosum in children". Pediatric dermatology 23 (6): 574–9. doi:10.1111/j.1525-1470.2006.00313.x. PMID 17156002. 
  20. ^ Syed TA, Goswami J, Ahmadpour OA, Ahmad SA (May 1998). "Treatment of molluscum contagiosum in males with an analog of imiquimod 1% in cream: a placebo-controlled, double-blind study". J. Dermatol. 25 (5): 309–13. PMID 9640884. 
  21. ^ Best Pharmaceuticals for Children Act, Public Law 107-109, January 4, 2002. http://www.fda.gov/RegulatoryInformation/Legislation/FederalFoodDrugandCosmeticActFDCAct/SignificantAmendmentstotheFDCAct/ucm148011.htm
  22. ^ a b c d DailyMed. Aldara (imiquimod) Cream for Topical use (Prescribing information): http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=7fccca4e-fb8f-42b8-9555-8f78a5804ed3
  23. ^ FDA. Label for Imiquimod (Aldara) from 03/22/2007 Efficacy Supplement with Clinical Data to Support. http://www.accessdata.fda.gov/drugsatfda_docs/label/2007/020723s020lbl.pdf
  24. ^ Katz, KA; Swetman, GL (2013). "Imiquimod, molluscum, and the need for a better "best pharmaceuticals for children" act". Pediatrics 132 (1): 1–3. doi:10.1542/peds.2013-0116. PMID 23796740.  Supplemental information.
  25. ^ Myhre, PE; Levy, ML; Eichenfield, LF; Kolb, VB; Fielder, SL; Meng, TC (2008). "Pharmacokinetics and safety of imiquimod 5% cream in the treatment of molluscum contagiosum in children". Pediatric dermatology 25 (1): 88–95. doi:10.1111/j.1525-1470.2007.00590.x. PMID 18304162. 
  26. ^ Scheinfeld N (March 2003). "Cimetidine: a review of the recent developments and reports in cutaneous medicine". Dermatol. Online J. 9 (2): 4. PMID 12639457. 
  27. ^ Langley JM, Soder CM, Schlievert PM, Murray S (July 2003). "Case report: Molluscum contagiosum. Toxic shock syndrome following cantharidin treatment". Can Fam Physician 49: 887–9. PMC 2214253. PMID 12901485. "... although pure cantharidin and flexible collodion can be purchased as separate items and mixed by clinicians" 
  28. ^ Gold, MH; Moiin, A (January 2007). "Treatment of verrucae vulgaris and molluscum contagiosum with photodynamic therapy". Dermatologic clinics 25 (1): 75–80. doi:10.1016/j.det.2006.09.015. PMID 17126744. 
  29. ^ Brown, M; Paulson, C; Henry, SL (Oct 15, 2009). "Treatment for anogenital molluscum contagiosum". American family physician 80 (8): 864. PMID 19835348. 
  30. ^ Vos, T (Dec 15, 2012). "Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010". Lancet 380 (9859): 2163–96. doi:10.1016/S0140-6736(12)61729-2. PMID 23245607. 

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