Involuting common warts. Clinical and histopathologic findings.

Patterns of regression in common warts were studied. Patients with multiple verrucae vulgaris lesions applied topical agents to the warts and were observed at regular intervals until the lesions disappeared. Regression took place without the warts turning black in all but one instance. All warts did not disappear simultaneously; some lesions persisted weeks after others had disappeared. Microscopic examination in five patients of a wart persisting after most had regressed demonstrated mononuclear cell infiltration, exocytosis, and degenerative epidermal changes. Failure to demonstrate cellular infiltration in regressing common warts in earlier studies was probably due to concentration on studying only warts that had turned black. The regression of some of the warts in patients with multiple common warts may serve as an indicator that involution is in progress. Utilization of this observation to recognize clinically the period of involution may make possible studies during the critical phase of the involutionary process.