Porokeratosis of mibelli of upper lip extending into oral mucosa

Abstract

Porokeratosis is a rare specific disorder of keratinization with distinct clinical and histopathological features with rare malignant degeneration. Clinically, it is characterized by papular lesions or annular plaques with central atrophy and peripheral keratotic ridge and histologically with the presence of cornoid lamellae. It mainly presents on the extremities, trunk, face, and very rarely on genitals and mucous membrane. Very few cases of porokeratosis with oral mucosal involvement have been reported in the past. A 50-year-old female presented with a well-demarcated, irregular plaque with atrophic center and peripheral keratotic margin with a thin furrow involving the left side of the upper lip, angle of mouth, and adjacent labial mucosa. The patient had a history of application of topical steroid preparations intermittently over a period of 2 years. The histopathological features showed characteristic cornoid lamellae. The involvement of mucosa is uncommon, and local immunosuppression caused by topical steroids may act as a predisposing factor.