Follicular Granular Parakeratosis: A Case Report, Literature Review, and Proposed Classification

Abstract

Granular parakeratosis (GP) is a distinctive acquired keratotic dermatosis that is usually presented with brownish-red hyperkeratotic papules and plaques in the intertriginous areas. Follicular involvement in GP could be either extending lesions from interfollicular epithelium or originating primarily from the follicular epithelium. The latter was named follicular GP and is considered an extremely rare condition. To our knowledge, there has been one reported case so far in the literature. We herein report the second case of follicular GP in a 52-year-old Thai man presenting with multiple tiny filiform hyperkeratotic papules on his face 2 weeks after using anti-melasma cream. We also propose a classification of GP based on its distinct clinical manifestations and histopathological findings.