What is the recommended management for chronic molluscum contagiosum (a viral skin infection) near the anus and buttocks?

Management of Chronic Molluscum Contagiosum Near Anus and Buttocks

For chronic molluscum contagiosum in the perianal and buttock region, physical removal methods—specifically cryotherapy with liquid nitrogen, curettage, or simple excision—are the recommended first-line treatments, and you should identify and treat all lesions including nascent ones to reduce recurrence risk. 1, 2

Initial Assessment

When evaluating perianal/buttock molluscum, you need to:

• Confirm the diagnosis by identifying characteristic dome-shaped, smooth-surfaced papules (2-5 mm) with central umbilication that are skin-colored, pink, or whitish 3
• Assess the extent of disease and count the number of lesions, as multiple large lesions with minimal inflammation may indicate immunocompromise 1, 2
• Screen for other sexually transmitted infections, as perianal/genital molluscum is often sexually transmitted in adults 3
• Consider HIV testing and immunocompromised state screening if lesions are extensive, recalcitrant, or unusually severe 1, 2

First-Line Treatment Algorithm

Physical Removal Methods (Preferred)

The American Academy of Ophthalmology recommends physical removal as first-line therapy 1, 2:

• Cryotherapy with liquid nitrogen is highly effective and recommended 2, 4
• Curettage (incision and curettage or simple excision) provides immediate removal 1, 2
• Excision and cautery is equally effective as other physical methods 2

Critical principle: Treat ALL lesions including nascent ones during the same session, as reducing viral load allows the host immune response to eliminate residual virus 1, 2

Topical Chemical Treatments (Alternative)

If physical removal is not feasible or patient-preferred:

• 10% potassium hydroxide solution applied topically has similar efficacy to cryotherapy and is recommended by the American Academy of Pediatrics 1, 5
• Cantharidin has shown effectiveness in observational studies, though randomized trial evidence is limited 1, 5
• Podophyllotoxin is mentioned as an option for genital molluscum in the European guideline 3

What NOT to Use

Imiquimod 5% cream should NOT be used, as high-quality evidence from multiple large trials shows no benefit over placebo for clinical cure at 12,18, or 28 weeks, despite causing significantly more application site reactions (NNTH = 11) 1, 6. While one older small study suggested benefit 7, and another showed equivalence to potassium hydroxide 8, the most recent and highest quality evidence clearly demonstrates lack of efficacy 6.

Special Considerations for Perianal Location

• In pregnancy, physical procedures like cryotherapy are safe 3
• For sexually transmitted cases, the 2020 European guideline emphasizes screening for other STIs 3
• Watchful waiting is reasonable in immunocompetent patients who prefer to avoid treatment, as spontaneous resolution typically occurs within 6-12 months (though can take up to 5 years) 1, 5, 3

When to Refer

Refer to dermatology if 1, 2:

• Extensive or recalcitrant disease despite appropriate treatment
• Confirmed or suspected immunocompromised state
• Uncertainty about diagnosis or presence of other suspicious lesions

Follow-Up

• Follow-up is not usually necessary unless new lesions develop or the patient is immunocompromised 2
• Monitor for recurrence at the treatment site, as incomplete removal of nascent lesions is a common pitfall 1

Common Pitfalls to Avoid

• Failing to treat nascent lesions during initial treatment session leads to apparent "recurrence" 1
• Using imiquimod based on older literature when high-quality evidence shows no benefit 6
• Missing underlying immunocompromise in patients with extensive disease 1, 2
• Not screening for other STIs in adults with genital/perianal molluscum 3