Low-dose oral zinc supplementation leading to resolution of recalcitrant common warts: A case report with 5-year follow-up.

INTRODUCTION: Verruca vulgaris, or common wart, is cause by the human papillomavirus (HPV). Cases may be recalcitrant, and may reflect deficient cell-mediated immunity, one cause of which could be low serum levels of zinc, which plays a crucial role in lymphocyte development and function. Here, we report a case of recalcitrant common warts in a zinc-deficient man responding to oral zinc supplementation.
CASE SUMMARY: A then 44-year-old man presented with hyperkeratotic verrucous papules on the left elbow, clinically and histopathologically diagnosed to be verucca vulgaris. Initial treatment with electrosurgery was followed by recurrence on the same site several weeks later. Further recurrences would be noted despite treatment with several sessions of electrosurgery and cryotherapy, with eventual involvement of both forearms and shins. Other treatment modalities tried by the patient included pulsed dye laser, imiquimod and a traditional topical medication containing salicylic acid. HPV typing showed HPV genotype 6. Primary immunodeficiency panel done on 2 separate occasions showed decreased CD4 count with reversed CD4:CD8 ratio, with decreased natural killer count. Whole blood and serum zinc levels were also found to be decreased on 2 separate occasions. The patient was then started on oral zinc picolinate 50mg (10mg elemental zinc) daily, eventually shifting to chelated zinc oxide 15mg (12mg elemental zinc) daily, without any other intervention. The only adverse effect reported was nausea. Follow-up at 1 year and 5 years after starting oral zinc supplementation has shown no recurrence of warts.
CONCLUSION: Recent years have seen a surge of interest in high-dose oral zinc as monotherapy for recalcitrant warts. Although there is still insufficient evidence to support this, the positive response demonstrated in this case corroborates the immunomodulatory role that zinc may play for this indication. In addition, this case may show that even low doses of zinc may be beneficial as either monotherapy or as adjunct in the treatment of recurrent common warts. It is recommended that randomized clinical trials with better quality, comparing different doses and formulations of oral zinc for common warts be done, while taking into account corresponding elemental zinc values.