Differential Diagnosis for Warts in Children
Primary Diagnostic Approach
The definitive diagnostic test is paring down the lesion with a scalpel blade, which reveals pinpoint bleeding from exposed capillary loops in warts versus a translucent central core in corns or homogenous thickened keratin without bleeding in calluses. 1
Key Differential Diagnoses
Warts (Verruca Vulgaris)
- Caused by HPV infection (types 1,2,4,27, or 57 for common warts; HPV-1 and HPV-2 most common for plantar warts) 1, 2
- Appear as hyperkeratotic papulonodules with disrupted or absent skin lines across the lesion 1, 3
- Paring reveals pinpoint bleeding as capillary loops of elongated dermal papillae are exposed—this is pathognomonic 4, 1, 3
- Can occur on hands, feet, face, periungual areas, or any epithelial surface 4
- Usually painless unless on pressure-bearing surfaces 4
Corns (Clavus)
- Occur at pressure points, typically on feet but can occur on hands with repetitive trauma 1, 3
- Paring reveals a translucent central core without bleeding 1, 3
- Preserved skin lines may be visible 1
- Distinguished from warts by close inspection after paring 4
Calluses
- Characterized by diffuse, yellowish thickening at pressure areas 1, 3
- Paring shows homogenous thickened keratin without bleeding 1, 3
- Skin lines remain intact 1
Molluscum Contagiosum
- Benign epidermal eruptions resulting from viral infection, usually self-limited 5
- Appear as umbilicated papules, distinct from the hyperkeratotic appearance of warts 5, 6
- More extensive in immunocompromised children 5
Lichen Planus
- Hyperkeratotic lesions on limbs that may cause confusion with warts 4
- Flat (plane) warts may need to be distinguished from lichen planus 4
- Requires close inspection and potentially biopsy for definitive diagnosis 4
Other Considerations in Specific Contexts
- Angiokeratoma: May mimic warts on limbs 4
- Actinic keratoses: Occur on chronically sun-exposed skin (dorsa of hands), present as discrete patches of erythema and scaling, typically in older individuals—not typical in children 3
- Seborrhoeic keratoses: Thin lesions that may resemble plane warts 4
Diagnostic Technique
Follow this systematic approach:
- Soak the lesion in warm water to soften tissue before examination 1, 3
- Pare down carefully with a scalpel blade, removing superficial layers 1, 3
- Inspect closely for:
- Assess skin lines: Disrupted in warts, preserved in corns/calluses 1, 3
Special Considerations in Children
Immunocompromised States
- Warts may be large, extensive, and resistant to treatment in immunosuppressed children 4
- Unusually severe or prolonged warts should prompt consideration of underlying immune deficit (lymphoma, idiopathic CD4 lymphocytopenia, HIV infection) 4
Natural History
- 50% of warts clear spontaneously within 1 year in children, and two-thirds by 2 years 1, 3, 2
- Expectant management is entirely acceptable for immunocompetent patients with asymptomatic warts 1, 3, 2
Critical Pitfalls to Avoid
- Never use chemical corn removers or plasters on diabetic patients due to high complication risk 1, 3
- Avoid overdebridement of any lesion, which can cause pain and tissue damage 1, 3
- Do not use destructive treatments on facial warts without extreme caution due to scarring risk 1, 3
- Recognize that wart treatments do not eradicate HPV infection—recurrence is common, usually at least 25% within 3 months with all modalities 1, 3
- HPV can spread through direct contact or via the environment and may remain infectious outside the body for months or years 3, 2
Treatment Implications Based on Diagnosis
For Confirmed Warts
- Salicylic acid 15-40% topical paints or ointments as first-line treatment (Level of evidence 1+, Strength A) 1, 3
- Cryotherapy with liquid nitrogen fortnightly for 3-4 months as alternative 1, 3, 2
- Expectant management is acceptable for asymptomatic warts in immunocompetent children 1, 3, 2