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Presentation

Treatment Approaches for Periungual and Subungual Warts

Description

The speaker reviews treatment of periungual and subungual warts, emphasizing that these cases are often frustrating because they frequently require multiple treatments, can recur, and destructive procedures may cause nail dystrophy or disfigurement. Treatment choice depends on lesion size and location, number of lesions, whether the wart is isolated or hidden under the nail, patient age, immune status, prior treatment failures, and whether biopsy is needed to rule out squamous cell carcinoma in resistant cases. For isolated cutaneous warts, destructive methods such as liquid nitrogen, curettage, or electrodesiccation are used first. For periungual and subungual warts, the preferred first-line approach is immunotherapy, especially topical contact allergens such as squaric acid, applied weekly with careful instruction to induce a controlled inflammatory reaction; improvement may take about three months. Second-line therapy is intralesional bleomycin, which works by DNA damage and is highly effective for recalcitrant warts, though it can cause pain, redness, swelling, and black eschar as the wart sloughs off. Contraindications include children, pregnancy, vascular disease, and immunodeficiency. As a last resort, the speaker uses cidofovir, and mentions 5-FU as another DNA-damaging option. The talk also notes adjuncts like zinc supplementation in deficient patients and cimetidine, though evidence for cimetidine and wart vaccines is weak or mixed.

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Conclusions

Periungual and subungual warts are often frustrating to treat, commonly recur, and require therapy choices tailored to lesion location, size, number, patient age, immune status, and prior treatment failure.
Destructive treatments such as cryotherapy, curettage, surgery, and laser are reasonable for isolated cutaneous warts but are less successful for periungual or subungual lesions and can cause nail dystrophy or disfigurement.
Because repeated treatment failures can indicate an alternative diagnosis, recalcitrant nail-unit lesions should prompt consideration of biopsy to rule out squamous cell carcinoma.
For periungual and subungual warts, topical contact immunotherapy is favored as first-line treatment, with inflammation rather than the agent itself driving wart clearance.
Intralesional bleomycin is an effective second-line option for resistant warts, with high reported cure rates but expected pain, necrosis, and rare adverse effects requiring careful technique and patient selection.
Cidofovir and 5-fluorouracil are reserved as later-line options for stubborn warts when other treatments fail.
Systemic adjuvants such as zinc supplementation or cimetidine may be considered, but the evidence for cimetidine and HPV vaccination as wart therapy is weak or controversial.
Overall, the presentation supports a treatment algorithm that escalates from destructive therapy for isolated lesions to immunotherapy, bleomycin, and then cidofovir for periungual or subungual recalcitrant warts, with biopsy when response remains poor.

W.B. Shelley, Arch Dermatol. 1991 Feb;127(2):234-6.