Molluscum contagiosum is a viral infection that is exclusive to humans. It is characterized with the presence of small elevated lesions called papules. These papules have a waxy surface and are seen on various parts the body such as the face, trunk, arms and legs. It can also affect the armpits but does not involve the palms. It has also been found to affect the eyelids.
Cause of molluscum contagiosum
Molluscum contagiosum is caused by a viral infection. The portal of entry of the riders into the body is usually through some form of break in the skin. Having low levels of immunity such as in the case of HIV virus infections can also make an individual prone to developing molluscum contagiosum. In such individuals, the lesions are a lot more widespread. Studies have also shown the development of molluscum contagiosum affecting the eyelids of both eyes following treatment of rheumatoid arthritis with specialist drugs such as methotrexate.
Molluscum contagiosum is caused by a DNA poxvirus called the molluscum contagiosum virus (MCV). MCV has no 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 and often sexually transmitted. This common viral disease has a higher incidence in children, sexually active adults, and those who are immunodeficient. The infection is most common in children aged one to ten years old.
The virus commonly spreads through skin-to-skin contact. This includes sexual contact or touching or scratching the bumps and then touching the skin. Handling objects that have the virus on them (fomites), such as a towel, can also lead to in infection. The virus can spread from one part of the body to another or to other people. The virus can be spread among children at day care or at school. Molluscum contagiosum is contagious until the bumps are gone; which, if untreated, could be up to 6 months or longer. The time from infection to the appearance of lesions can range up to 6 months, with an average incubation period between 2 and 7 weeks.
Clinical features of molluscum contagiosum
Multiple small papules with a waxy/shiny surface become clearly evident on the body, and are particularly noticeable on the eyelids. Typically, scratching the lesions can make them worse as more and more lesions form along the line of scratching. This is a typical phenomenon called as Koebner phenomenon. Upon examination, the lesions are flesh colored and vary between 2 to 5 mm in size. Patients with poor immune levels tend to have multiple lesions all over the body. The involvement of the eyelids and the face is commonly seen in children whereas the involvement of the groin area is seen in adults. Associated with molluscum contagiosum are other skin conditions such as atopic dermatitis and eczema.
Diagnosis molluscum contagiosum
A diagnosis of molluscum contagiosum can be made by tests such as polymerase chain reaction and excisional biopsy. A biopsy demonstrates the presence of specific structures within the lesions called inclusion bodies. These bodies can be stained using specific dyes to help identify them under a microscope.
Diagnosis is also made on the clinical appearance. Molluscum contagiosum lesions are flesh-colored, dome-shaped, and pearly in appearance. They are often 1–5 millimeters in diameter, with a dimpled center. They are generally not painful, but they could itch or become irritated. Picking or scratching the bumps could lead to further infection or scarring. In about 10% of the cases, eczema develops around the lesions. They could occasionally be complicated by secondary bacterial infections. In some cases the dimpled section could bleed once or twice. The viral infection is limited to a localized area on the topmost layer of the epidermis.
In a process called auto-inoculation, the virus can spread to neighboring skin areas. Children are particularly susceptible to auto-inoculation, and could have widespread clusters of lesions.
Treatment molluscum contagiosum
Once the virus containing head of the lesion has been destroyed, the infection is gone. The central waxy core contains the virus. One form of treatment is called curettage and involves administration of an anaesthetic agent followed by removal of the lesion completely.
Most cases of molluscum contagiosum tend to resolve themselves in a few months. Depending on the severity of the case, it is possible that molluscum contagiosum impacting eyelids could be managed conservatively without performing any intervention. Although other treatments are available to manage molluscum contagiosum, detailed studies have shown that there does not appear to be any additional benefit of using these treatments (skin creams, anti-viral agents and herbal medicines) in comparison to doing nothing at all.
Molluscum contagiosum is an condition that can affect various parts of the body. The involvement of the eyelids is more often seen in children and usually resolves by itself. Specific treatments can be offered though recurrence rates can be high.