Molluscum contagiosum

Molluscum contagiosum

Cause

This common pox virus infection can be spread by direct contact; e.g. sexually or by sharing a towel at the swimming bath.

Presentation and course

The incubation period ranges from 2 to 6 weeks. Often several members of one family are affected. Individual lesions are shiny, white or pink, and hemi-spherical; they grow slowly up to 0.5 cm in diameter. A central punctum, which may contain a cheesy core, gives the lesions their characteristic umbilicated look.

On close inspection a mosaic appearance may be seen. Multiple lesions are common (Fig. 14.30) and their distribution depends on the mode of infection. Atopic individuals and the immunocompromised are prone to especially extensive infections, spread by scratching and the use of topical steroids.

Untreated lesions usually clear in 6–9 months, often after a brief local inflammation. Large solitary lesions may take longer. Some leave depressed scars.

Complications

Eczematous patches often appear around mollusca. Traumatized or overtreated lesions may become secondarily infected.

Differential diagnosis

Inflamed lesions can simulate a boil. Large solitary lesions in adults can be confused with a keratocan-thoma, an intradermal naevus, or even a cystic basal cell carcinoma. Confusion with warts should not arise as these have a rough surface and no central pore.

Investigations

None are usually needed, but the diagnosis can be confirmed by looking under the microscope for large swollen epidermal cells, easily seen in unstained pre-parations of debris expressed from a lesion.

Treatment

Many simple destructive measures cause inflamma-tion and then resolution. They include squeezing out the lesions with forceps, piercing them with an orange stick (preferably without phenol), and curettage. Liquid nitrogen may also be helpful.

These measures are fine for adults, but young children dislike them and it is reasonable to play for time using imiquimod or chlortetracycline cream, or instructing the mother carefully how to apply a wart paint once a week to lesions well away from the eyes. Sometimes a local anaesthetic cream (EMLA;), under polythene occlusion for an hour, will help children to tolerate more attacking treatment. Sparse eyelid lesions can be left alone but patients with numerous lesions may need to be referred to an ophthalmologist for curettage. Common sense measures help to limit spread within the family.