What are the differential diagnoses for a wart on the face and how should it be evaluated and managed?

Differential Diagnosis of Facial Warts

When evaluating a suspected wart on the face, the critical differential diagnoses include seborrhoeic keratoses, actinic keratoses, squamous cell carcinoma, lichen planus, and plane (flat) warts, with the diagnostic approach centered on clinical inspection, paring to reveal pinpoint bleeding, and a low threshold for biopsy of any atypical or treatment-resistant lesion. 1

Primary Differential Diagnoses

Seborrhoeic Keratoses

• Seborrhoeic keratoses present as "stuck-on," waxy lesions with variable pigmentation, occur predominantly in older adults, and critically retain normal skin-line patterns—unlike warts which disrupt dermatoglyphics. 1
• These lesions are benign and do not require treatment unless symptomatic or cosmetically bothersome. 1

Actinic Keratoses

• Actinic keratoses arise on chronically sun-exposed facial skin and appear as discrete erythematous, scaling patches with a rough, sandpaper-like texture. 1
• They occur typically in middle-aged and elderly individuals with significant sun exposure history. 1
• These lesions represent premalignant changes and warrant treatment or close monitoring. 1

Squamous Cell Carcinoma

• Squamous cell carcinoma must be suspected in any non-healing, treatment-resistant hyperkeratotic facial lesion, particularly in elderly or immunosuppressed patients. 1
• Typical features include ulceration, bleeding, rapid growth, and failure to respond to standard wart therapy—all of which constitute red-flag signs mandating biopsy. 1
• In immunosuppressed patients (organ transplant recipients, HIV-positive individuals), there is elevated risk of HPV-associated SCC requiring early biopsy of atypical lesions. 1

Lichen Planus

• Lichen planus presents with pruritic, violaceous, flat-topped papules; when hyperkeratotic, the presence of Wickham striae and associated itching helps distinguish it from asymptomatic warts. 1
• Plane warts on the face may need to be distinguished from lichen planus or thin actinic or seborrhoeic keratoses. 2

Plane (Flat) Warts

• Plane warts are a distinct clinical variant of viral warts that commonly affect the face and may be confused with other flat lesions. 2
• These lesions are typically multiple, small, and slightly elevated. 3

Diagnostic Approach

Clinical Examination

• Soak the lesion in warm water to soften tissue, then gently pare down with a scalpel blade; pinpoint bleeding from exposed capillary loops is pathognomonic for a wart. 1
• Absence of bleeding with a translucent core suggests a corn (unlikely on face), while homogeneous thickened keratin without bleeding indicates a callus or other hyperkeratotic condition. 1
• Assess for disrupted skin lines (dermatoglyphics), which are characteristic of warts, versus preserved lines in seborrhoeic keratoses or other lesions. 1

Dermoscopy Features

• Dermoscopy can improve diagnostic accuracy for clinically nonclassical cutaneous warts by revealing papillomatous growth, dotted and linear vessels, hairpin-like vessels, and bleeding spots. 4
• The presence of black dots (capillary thrombosis) has the highest diagnostic reliability for warts. 5

Red-Flag Features Requiring Biopsy

• Lesions that fail to respond to standard wart therapy, display atypical symptoms such as pruritus, are pigmented and enlarging, or occur in immunosuppressed patients constitute absolute indications for biopsy. 1
• Unusually severe or prolonged warts may signal underlying immunosuppression (lymphoma, idiopathic CD4 lymphocytopenia, HIV infection) or malignant transformation. 2, 1
• Biopsy is mandatory before aggressive treatment of any suspicious lesion to exclude squamous cell carcinoma. 1

Management Considerations for Facial Warts

Treatment Cautions

• Never use destructive treatments on facial warts without extreme caution due to high scarring risk. 1
• Weaker cream preparations of salicylic acid are sometimes used for facial warts, but without trial evidence to confirm efficacy. 2
• Cryotherapy with liquid nitrogen can be used but requires careful application to minimize scarring. 2

Expectant Management

• Depending on site and size, facial warts may be just a minor nuisance, and if the patient is immunocompetent, an expectant approach to management is entirely acceptable. 2
• Approximately 50% of warts clear spontaneously within 1 year in children and two-thirds by 2 years. 1
• In adults, warts can be more persistent, sometimes lasting 5–10 years without treatment. 6

When Warts Require Treatment

• Facial warts may be a major cosmetic concern and source of embarrassment, warranting treatment under these circumstances. 2
• Treatment should be guided by anatomic site, size, number of warts, expense, efficacy, convenience, and potential adverse effects. 1

Special Populations

Immunosuppressed Patients

• In immunosuppressed patients, warts tend to be larger, more extensive, and treatment-resistant; these patients also have elevated risk of HPV-associated SCC and merit early biopsy of atypical lesions. 1
• Warts may be the presenting feature of milder immunosuppressed states such as lymphoma, idiopathic CD4 lymphocytopenia, or HIV infection. 2
• In epidermodysplasia verruciformis (EV), a familial tendency to develop scaly and plane wart-like keratotic facial lesions frequently progresses to squamous cell cancer in early adult life. 2

Critical Pitfalls to Avoid

• Do not assume all hyperkeratotic facial lesions are benign warts—maintain a high index of suspicion for actinic keratoses and squamous cell carcinoma, especially in elderly or sun-damaged skin. 1
• Avoid aggressive destructive therapy on the face without definitive diagnosis, as scarring is permanent and may be worse than the original lesion. 2, 1
• Recognize that wart treatments do not eradicate HPV infection, and recurrence is common (at least 25% within 3 months with all modalities). 1
• HPV can spread through direct contact or via the environment and may remain infectious outside the body for months or years. 1, 6