Abstract
BACKGROUND: Granular parakeratosis is a rare disorder characterized by erythematous-brown hyperkeratotic papules and erythematous patches with scaling, occurring predominantly in the flexures and sites of occlusion. While the exact underlying pathogenesis remains unknown, there has been a wide variety of precipitating factors and treatment options reported in the literature. OBJECTIVE: We systematically reviewed and identified precipitants of granular parakeratosis, as well as its clinical and histologic features and treatment outcomes. METHOD: A comprehensive literature search was conducted using MEDLINE and Embase in March 2021. RESULTS: A total of 60 studies with 129 patients were included for analysis. An inciting factor was identified in 53.4%, the most common being topical agents including zinc oxide (17.1%), deodorant/antiperspirant (15.5%), and those containing benzalkonium chloride (7.0%). The majority presented with bilateral (68.2%) eruption of hyperkeratotic papules or erythematous patches and plaques, most frequently involving the axilla (56.5%). The prevailing histologic feature was retained keratohyalin granules within the stratum corneum in punch biopsy (97.2%) and curette (100%) specimens. Treatment options with reported success ranged from topical corticosteroids and systemic antibiotics to surgical interventions. CONCLUSION: We provide a systematic review of reported precipitants, clinical features, and treatment options that clinicians should consider when granular parakeratosis is considered.