Molluscum contagiosum virus is the only circulating poxvirus specific to humans and having a worldwide distribution. It is known to cause benign skin changes in young children, and less commonly in adults (mostly transmitted sexually). Extensive infections may be observed in immunosuppressed adults.
Generally, treatment of molluscum contagiosum is not necessary, as spontaneous resolution of this condition is the norm in the majority of cases. Affected individuals only need to be reassured that the lesions may be present for a few months before they resolve and heal naturally. However, there are certain circumstances where treatment endeavors should be considered, mainly due to cosmetic issues or when confronted with underlying atopy.
The end-goal of any approach is the complete destruction of the lesion to halt further spread of the disease and auto-inoculation, which is why most of the treatments are mechanical in nature to traumatize the lesions. Recently, several antiviral and immune-modulating options have been added to our therapeutic armamentarium.
One of the most straightforward approaches is removing the lesions by eviscerating their cores with an instrument such as a scalpel, the edge of a glass slide or a sharp tooth pick. Adhesive tape can also be used by repeatedly applying and removing it for 10-20 cycles, although its use may be linked to secondary skin infections.
Cryotherapy with liquid nitrogen is another option, but this approach can be painful. Moreover, repeat applications on a weekly basis are often necessary, and in some instances local anesthesia is warranted. However, it is completely safe for use, even in pregnant women.
The utilization of pulsed dye laser has shown promising results, as up to 99% of lesions respond after just one treatment. This type of approach is well-tolerated without any adverse side effects; nevertheless, this method is less cost-effective than other treatment avenues.
Currently available and effective topical treatments include podophyllotoxin cream (0.5%) and imiquimod cream (5%). Although no toxic effects have been demonstrated for these agents thus far, some local irritation may ensue, and their use in pregnancy is not advocated.
A 25% suspension of podophyllin in a tincture of alcohol or benzoin may also be applied once a week on the affected area. However, its use should be under medical supervision, as there are potential side effects such as severe erosive damage in the adjacent skin (with possible scarring) and systemic effects such as leukopenia, thrombocytopenia and peripheral neuropathy.
A solution comprised of 0.9% of cantharidin and acetone is a blister-inducing agent that is applied sparingly to the dome of the lesion, where it is left for at least four hours before being washed off. If tolerated, this type of treatment is repeated every week until lesions clear, although in most cases one to three treatments are sufficient.
Tretinoin cream (either 0.1% or 0.05%) has been shown to be effective when applied once or twice every day to mollusca lesions in children or adults. Erythematous changes are commonly observed in previously treated lesions. These are less prominent when 0.05% cream is used for treatment purposes.
Cimetidine, which is an oral histamine H2-receptor antagonist, acts by stimulating delayed-type hypersensitivity. Although originally used to prevent and treat the symptoms of heartburn, some studies have shown that it may lead to the resolution of molluscum contagiosum when used twice a day for two months.
Likewise, different studies have shown that the introduction of highly active antiretroviral therapy (HAART) and the subsequent restoration of the immune system in patients with human immunodeficiency virus (HIV) lead to the disappearance of lesions. But the exact opposite can also happen – during the initial phase of immunologic reconstitution there is a possibility of clinical deterioration (known as immune reconstitution inflammatory syndrome) that may give rise to molluscum contagiosum and other cutaneous disorders.
As already mentioned, spontaneous healing is a common outcome in patients with molluscum contagiosum, although it may sometimes take several years. In any case, patients must be advised to avoid scratching the lesion, and stop sharing personal items and grooming implements.
Measures to control the activity of infected cases are not required, since the risk of transmission is very low. However, in an outbreak situation it is quite reasonable to advise or consider suspending any sporting activities that an infected individual may be currently pursuing.