Molluscum contagiosum and viral warts — viva

Opening (2 minutes)

The candidate should recognise the two distinct diagnoses in this atopic child and commit to a conservative-first plan while addressing the mother's anxiety. The axillary lesions are molluscum contagiosum (a poxvirus producing pearly umbilicated papules) and the thumb lesion is a common viral wart (human papillomavirus producing a rough hyperkeratotic papule). Both are benign, self-limiting and transmissible, and the atopic dermatitis and swimming are relevant risk factors. [2]

Branch 1 — diagnosis and pathophysiology

Examiner: "What are these two lesions, and why do they behave the way they do?" The expected answer names Molluscum contagiosum virus as a DNA poxvirus of the genus Molluscipoxvirus and describes the pearly umbilicated papule with molluscum (Henderson-Patterson) bodies, and names human papillomavirus as the cause of the wart with koilocytes, hyperkeratosis and acanthosis on histology. A strong candidate explains that both evade immunity until a cell-mediated Th1 response switches on, which is the biological basis for their long indolent course and eventual spontaneous resolution. [2]

Branch 2 — expectant versus active treatment and the anxious parent

Examiner: "She wants them frozen off today. How do you respond?" The candidate should not simply comply. The correct response is shared decision-making grounded in natural history: molluscum has a median resolution time of about 13 months with most children clear within two years, and about two-thirds of childhood warts resolve spontaneously within two years, so expectant care is the evidence-based default. I would address the fear of scarring directly — the lesions rarely scar, but over-aggressive cryotherapy, cantharidin runoff or curettage can. [3]

If active treatment is warranted by bother, the wart is treated with salicylic acid 12 to 26 per cent then cryotherapy every two to four weeks, and the molluscum with in-office cantharidin 0.7 per cent, potassium hydroxide 10 per cent, or the newer home topical berdazimer 10.3 per cent gel. I would not use imiquimod for molluscum, because randomised trials showed no benefit over placebo. [8]

Branch 3 — red flags and special situations

Examiner: "What would change your approach?" The candidate should name the red flags. Extensive, confluent or giant molluscum, or a wart that bleeds, ulcerates or resists twelve weeks of therapy, should prompt investigation for immunodeficiency (HIV, DOCK8, combined immunodeficiency) and for a carcinoma mimic (verrucous or squamous cell carcinoma), with biopsy of atypical lesions rather than escalation of destructive therapy. Ano-genital lesions require a safeguarding-aware assessment without any presumption of abuse. A strong candidate closes by stating the unifying principle: be kinder than the disease. [7]

Closing (1 minute)

Summarise the plan: confirm the two diagnoses clinically, default to expectant care with hygiene advice and review, address the mother's fear of scarring, offer an evidence-based active option chosen with her if the lesions are bothersome (salicylic acid then cryotherapy for the wart; cantharidin, potassium hydroxide or berdazimer for the molluscum), and give a clear safety-net to return for rapidly growing, bleeding or extensive lesions. [2]