[Granular parakeratosis]

Granular parakeratosis is a rare entity that results from an acquired disorder of keratinization. Clinically presents as dark erythematous plaques, occasionally pruritic, that usually involve the axilla and other intertriginous areas. The pathology is characteristic and consists of thickening of the stratum corneum with compact parakeratosis and retention of keratohyaline granules, whereas the stratum granulosum is preserved. The etiology is unknown although some factors such as irritating physical or chemical agents have been implicated. Treatment response is variable. We report a new case in a 50-year-old woman with brownish and hyperkeratotic plaques on both axillae, of two years duration, with a compatible pathology that showed a favorable response to tacalcitol.