Uncommon Presentation of Pityriasis Rubra Pilaris of the Scalp: Clinical, Trichoscopic, and Histopathologic Features and Review of the Literature.

Pityriasis rubra pilaris (PRP) presents a diagnostic challenge due to its varied clinical manifestations and the scarce literature on scalp involvement. This article presents a case report of a 59-year-old female with PRP solely affecting the scalp, detailing its clinical, trichoscopic, and histopathological features. Trichoscopy revealed a novel finding of white-silvery scales forming hair casts with a triangular shape, distinct from the existing literature. A literature review comparing our findings with pertinent articles underscored the uniqueness of our case. We discuss differential diagnoses and treatment options, based on available evidence. Our case highlights the importance of understanding scalp manifestations in PRP, enhancing diagnostic accuracy, and improving treatment strategies for this rare condition. Furthermore, the review of the literature compares our observations with available case reports and case series, outlining differential diagnoses and trichoscopic and histopathological diagnostic approaches to PRP, enriching overall clinical knowledge of PRP.