Viral warts and molluscum contagiosum

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Examine surface, skin lines, capillary dots, central umbilication, body site and total burden. Dermoscopy can disclose red-black dots in warts and a central pore with polylobular white structures in molluscum. In darker skin, lesions may be hyperpigmented and post-treatment hypopigmentation is more apparent, so procedural risk belongs in consent.

No-treatment is often best. Most childhood molluscum clears over months, sometimes longer, and many warts resolve through immune recognition. Treat when pain, functional impairment, spread, eczema, stigma or patient preference outweighs discomfort and scarring risk. Explain that visible inflammation around molluscum can herald clearance rather than infection.

Site changes management. Periocular molluscum can cause conjunctivitis and needs eye-aware removal; periungual wart destruction can injure the nail matrix; genital lesions need STI and safeguarding context. An atypical lesion that grows, ulcerates, bleeds or resists appropriate therapy should be sampled instead of receiving repeated cryotherapy.

Key points

Common warts are rough hyperkeratotic papules with interrupted skin lines and thrombosed capillary dots; plantar warts are flattened inward beneath callus.
Molluscum lesions are smooth, firm, pearly or skin-coloured domes with a central umbilication and often cluster around eczema.
Both are usually self-limiting: observation is a valid first choice when lesions are painless, confidently diagnosed and not at a high-risk site.
For non-facial cutaneous warts, daily salicylic acid under product directions for up to 12 weeks is a practical first treatment; protect surrounding skin and pare only safely.
Cryotherapy can be repeated every two to three weeks but causes pain, blistering and pigment change and is not automatically superior to patient-applied therapy.
Do not use ordinary wart acids on face, genitals or broken skin; anogenital lesions need sexual-health assessment and safeguarding appropriate to age and context.
Routine destructive treatment of molluscum in children is usually unnecessary; control surrounding eczema and discourage scratching, squeezing and shared towels.
Numerous giant or facial molluscum, extensive refractory warts or unusual adult onset can signal immune suppression and warrants targeted assessment.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Human papillomavirus

Cutaneous HPV enters microtraumatised epidermis and produces common, plantar, plane, filiform or anogenital warts according to viral type and site.

Molluscum contagiosum virus

A poxvirus infects epidermal keratinocytes through direct skin contact, shared items or autoinoculation and causes pearly umbilicated papules.

Barrier and exposure

Atopic eczema, shaving, scratching, barefoot communal surfaces and close contact promote acquisition or spread without implying poor hygiene.

Immune control

Cell-mediated immunity usually clears both infections; immune suppression can cause numerous, large, facial or treatment-resistant lesions.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
HPV epidermal proliferation
Viral proteins stimulate hyperkeratotic papillary growth, thrombosed capillaries and interruption of normal skin lines within a wart.
2
Pressure inversion
On soles, body weight pushes a plantar wart inward beneath callus, causing pain on compression and clustered mosaic plaques.
3
Molluscum body formation
Poxviral inclusions fill a smooth dome-shaped papule and create a central dell containing white keratinous material.
4
Immune-resolution inflammation
Molluscum may become red, itchy and crusted as host immunity clears it; inflammation alone does not prove bacterial infection.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Rough verrucous wart

A firm papule interrupts dermatoglyphics and reveals punctate thrombosed capillaries after gentle surface paring.

Plantar pressure lesion

A sole wart grows inward beneath callus and often hurts on lateral compression, unlike a corn with preserved lines.

Umbilicated molluscum

Smooth 2–5 mm domes have a central dell and white core, sometimes with a surrounding eczematous halo.

Inflamed clearing phase

Redness, crust and itch affecting existing molluscum without spreading warmth or systemic illness can reflect immune resolution.

Immune-suppression pattern

Dozens of large, confluent or facial molluscum or unusually refractory extensive warts warrants targeted immune assessment.

Malignant departureRed flag

Rapid growth, spontaneous bleeding, induration, ulceration or irregular pigment requires urgent diagnostic review and possible biopsy.

Red flags requiring action

Bleeding, ulceration, rapid growth, pigment asymmetry, fixation, diagnostic uncertainty, widespread giant lesions in immune compromise, periocular threat, anogenital lesions in a child or pregnancy-related genital disease requires specialist assessment.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Clinical and dermoscopic examinationFirst step
Why
Confirm wart or molluscum morphology and select a site-safe option.
Interpretation and limitations
Typical lesions need no laboratory test; dermoscopy supports but does not overrule suspicious evolution.
02
Safe surface paring
Why
Distinguish plantar wart capillary dots from a corn where clinically appropriate.
Interpretation and limitations
Avoid in diabetes, poor circulation, anticoagulation or uncertain anatomy; never create bleeding merely to prove diagnosis.
03
Biopsy of an atypical lesion
Why
Exclude squamous carcinoma, melanoma or another verrucous mimic.
Interpretation and limitations
Choose tissue that captures lesion architecture, consent for scar and pigment change and tell pathology about failed treatments.
04
Targeted immune assessment
Why
Investigate extensive, giant, facial or unusually persistent disease.
Interpretation and limitations
Use HIV testing with consent and other tests according to history; ordinary childhood molluscum needs no immune screen.
05
Sexual-health and safeguarding assessment
Why
Manage anogenital lesions, co-infection risk and possible transmission safely.
Interpretation and limitations
Interpret genital lesions by age, developmental stage and full context; do not make a safeguarding conclusion from morphology alone.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Callus or corn

Skin lines continue through a corn and direct vertical pressure hurts, whereas a plantar wart interrupts lines and may hurt with side-to-side squeeze.

Seborrhoeic keratosis

A waxy stuck-on adult lesion can resemble a wart; sudden multiplicity, atypia or uncertainty warrants dermoscopic or specialist review.

Skin cancer

Squamous carcinoma, keratoacanthoma and amelanotic melanoma can appear verrucous; growth, bleeding, ulceration, induration or failed treatment prompts biopsy.

Folliculitis or milia

Pustules centred on hairs and firm white keratin cysts lack the smooth central umbilication of molluscum.

Cryptococcosis in immune compromise

Umbilicated facial papules with systemic illness or advanced immune suppression can indicate disseminated fungal infection and require urgent sampling.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01ObservationChoose benign natural resolutionFirst stepTypical painless lesions are confidently diagnosed and cause little functional or psychosocial burden.

1Explain viral transmission and natural history, cover lesions for contact sport where practical and avoid picking, shaving over them or sharing towels.
2Treat surrounding eczema with appropriate anti-inflammatory and emollient care without applying steroid directly as a destructive viral treatment.
3Review if lesions change, become painful or affect eyes or genitals, and avoid promising an exact clearance date.

02Treat cutaneous wartUse one controlled destructive methodPreferredA non-facial, non-genital wart is painful, functionally troublesome or treatment is preferred.

1Soak and gently reduce loose callus, protect normal skin and apply a licensed salicylic-acid wart product daily for up to 12 weeks.
2Pause for painful erosion and stop if infection or severe dermatitis develops; do not use on neuropathic or poorly perfused feet without specialist advice.
3Consider cryotherapy every two to three weeks after consent for pain, blistering, scar and dyspigmentation if self-treatment fails or is unsuitable.

03High-risk site or hostRefer rather than destroy blindlyLesions are periocular, genital, periungual, atypical, giant, extensive or occur with immune compromise.

1Confirm diagnosis and assess vision, STI and safeguarding context, immune history and malignant warning features.
2Use dermatology, ophthalmology, podiatry or sexual-health expertise for site-specific treatment and biopsy when required.
3Address the underlying immune disorder and avoid repeated traumatic procedures that scar without achieving viral control.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

A patient-applied keratolytic first option for suitable common or plantar warts.

Salicylic acid wart paint

Apply once daily to the wart only after soaking and gentle removal of loose keratin, continuing for up to 12 weeks according to the selected product.

Protect surrounding skin; avoid face, genitals, broken skin, poor circulation and neuropathy, and stop for marked pain, ulceration or dermatitis.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Pain and functional loss

Plantar and periungual warts can impair walking, work and nail growth, while destructive treatment may add pain and scarring.

Molluscum dermatitis

Eczema around lesions drives itch, scratching and autoinoculation; treating the dermatitis can reduce spread and distress.

Secondary infection

Excoriation may introduce bacteria, but transient redness during immune clearance should not trigger antibiotics without pain, pus or spread.

Dyspigmentation and scar

Cryotherapy, acids, curettage and picking can leave lasting colour change or scar, particularly on face and richly pigmented skin.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Review pain, function, lesion size and new lesions rather than counting treatment blistering as efficacy.
During salicylic acid treatment, inspect surrounding skin for erosion and pause until the barrier recovers when irritation is excessive.
After cryotherapy, safety-net severe pain, spreading redness, pus and delayed healing and document pigment or scar change.
For molluscum, distinguish transient clearing inflammation from bacterial cellulitis and control eczema that drives scratching.
Escalate bleeding, ulceration, rapid growth, periocular symptoms or widespread disease in immune compromise.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Skin lines tell a story

Warts interrupt dermatoglyphics while callus often preserves them, a useful sole examination clue.

Molluscum redness may reassure

Inflammation around established papules can represent host immune clearance rather than treatment-requiring infection.

Pain is not required

Plantar warts may hurt, but asymptomatic lesions can be observed without loss of future treatment opportunity.

Procedure risk varies by tone

Cryotherapy-induced hypo- or hyperpigmentation may be prolonged and deserves explicit consent in every skin tone.

Failure can mean mimic

A solitary enlarging adult wart that resists treatment should trigger biopsy consideration rather than endless freezing.

11Common pitfallsFrequent interpretation and management errors.

01
Treating every childhood molluscum lesion painfully despite a benign self-limiting course.
02
Using salicylic acid on face or genitals and causing chemical injury.
03
Freezing an uncertain verrucous cancer repeatedly instead of obtaining histology.
04
Calling inflamed molluscum bacterial infection without pain, spreading warmth or pus.
05
Assuming anogenital lesions in a child prove one transmission route without full safeguarding assessment.