Dermatologists' Impressions of Spontaneously Regressing Verruca Plana Histopathology

Verruca plana in its regressing phase exhibits clinical and histological features distinct from classic verruca plana, but the ways in which these features should inform treatment plans are still under investigation. We conducted a retrospective single-center analysis of 25 patients with features of classic verruca plana, or plane warts, who exhibited self-remission within 4 weeks of skin biopsy. Measures included lesion sites, clinical findings preceding regression, and histological analysis. Histological analysis involved review by 2 dermatologists followed by impressions given by 4 board-certified dermatologists who were blinded to the clinical characteristics of the patients. Histopathological findings of regressing plane warts showed superficial perivascular infiltration (96%), spongiosis and exocytosis (84%), basal vacuolization (64%), parakeratosis (64%), apoptotic keratinocytes (60%), and lichenoid infiltration (44%). These findings were more compatible with the histological patterns of pityriasis lichenoides, lichen planus, and spongiotic eczema, rather than classic verruca plana. This suggests that regressing verruca plana may be included in the differential diagnosis of lesions exhibiting a lichenoid or spongiotic reaction, and observation may be a favorable treatment plan in these patients.