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DR8.5 | Molluscum Contagiosum Recognition — SDL Guide (Part 2)

Differential Diagnosis and Investigations

Molluscum Contagiosum: Differential Diagnosis and Investigations

Molluscum is usually a confident clinical diagnosis, and the differential is settled by reading the surface of the papule and, where present, its central dimple. The most important everyday distinction is from a viral wart: molluscum is smooth, dome-shaped and centrally umbilicated, whereas a wart is rough, verrucous and shows black dots with interrupted skin lines — quite different surfaces. Milia are tiny white keratin cysts without a central dell and are not infectious; closed comedones occur in an acne context; and a sebaceous (epidermoid) cyst is a deeper, larger, non-umbilicated nodule. A special caution applies in HIV: disseminated cryptococcosis (and other deep fungal infections) can produce umbilicated papules that mimic molluscum closely, so in an immunocompromised patient with atypical or rapidly progressive lesions a biopsy is warranted to avoid missing a serious infection. In routine cases, clinical diagnosis suffices; dermoscopy and biopsy are reserved for atypical, giant or immunocompromised presentations.

The differential and investigation points are:
- Viral wart: rough, verrucous, black dots, interrupted skin lines (vs smooth, umbilicated molluscum).
- Milia: tiny white keratin cysts, no central dell, not infectious; closed comedones: acne context.
- Sebaceous (epidermoid) cyst: deeper, larger, non-umbilicated nodule.
- In HIV — cryptococcosis / deep fungal infection: can mimic molluscum; biopsy atypical or progressive lesions to exclude it.
- Investigations: clinical diagnosis usually sufficient; dermoscopy (central pore, polylobular white-yellow structures, crown vessels) and biopsy (Henderson-Paterson bodies) for atypical/giant/HIV cases.

Inspection Clues: Molluscum vs Wart vs Milia vs Sebaceous Cyst

Management of Molluscum Contagiosum

Management of Molluscum Contagiosum

Management of molluscum is guided by the clinical context, because the right action differs sharply between a healthy child, an adult with a sexually transmitted infection, and an immunocompromised patient. In immunocompetent people — especially children — molluscum is self-limiting, often clearing over months, so watchful waiting with reassurance is a legitimate and often preferred option that avoids painful procedures in young children. When treatment is wanted, it is largely physical or topical: physical destruction (cryotherapy, curettage, electrocautery) or topical agents that provoke resolution. In sexually active adults, treating genital lesions and counselling on sexual transmission and other STIs is appropriate. The most important context-specific principle is in HIV/immunocompromise: extensive molluscum reflects poor immunity, topical and physical treatments alone are often ineffective, and restoring immunity with antiretroviral therapy (ART) is the key intervention that brings the lesions under control. Throughout, counsel patients to avoid scratching, since autoinoculation spreads the infection.

The management principles are:
- Children/immunocompetent: often self-limiting — watchful waiting and reassurance are appropriate; avoid overtreatment.
- Physical destruction: cryotherapy, curettage, electrocautery; topical options include trichloroacetic acid, imiquimod, and potassium hydroxide (KOH) solution.
- Sexually active adults: treat genital lesions; counsel on sexual transmission and screen for other STIs.
- HIV / immunocompromised: antiretroviral therapy (ART) to restore immunity is the key intervention; topical/physical treatments are less effective without immune recovery.
- Counsel: avoid scratching (prevents autoinoculation), avoid sharing towels/sponges; the condition is contagious by contact.

Self-Assessment: Molluscum Contagiosum Recognition

Molluscum Contagiosum: Morphological Recognition, Clinical Contexts, and Management Pathway

The aim of this closing section is to confirm that you can recognise molluscum contagiosum by its umbilicated papule, read its clinical context, and separate it from warts and milia before choosing management. Recognition is an ordered reading: identify the pearly, dome-shaped papule with a central dell; place it in context (a healthy child, a sexually active adult, or an immunocompromised patient); run the key differentials (smooth umbilicated molluscum versus rough black-dotted wart, versus tiny non-umbilicated milia); and only then decide between watchful waiting, physical/topical treatment, STI counselling, or — in HIV — immune restoration with ART. The scenarios you should be able to handle include the scattered crops of a child's molluscum, the genital lesions of an adult needing STI screening, and the extensive giant facial molluscum that should trigger HIV testing. Use the self-check below to rehearse moving from lesion to context to management.

For each scenario, ask in order:
- Is the papule smooth, dome-shaped and centrally umbilicated (molluscum) rather than rough and black-dotted (wart) or a tiny white cyst (milium)?
- In which context does it appear — child, sexually active adult, or immunocompromised patient?
- Does the context demand STI screening, or does an extensive/giant/atypical pattern demand HIV testing?
- Is watchful waiting appropriate, is physical/topical treatment indicated, or is immune restoration (ART) the key intervention?