The pityriasis spectrum: An evidence-based review of pathogenesis, clinical heterogeneity, and emerging therapeutics

The nomenclature within dermatology frequently utilizes descriptive clinical terms to group heterogeneous conditions. The term pityriasis, derived from the Greek root referring to bran denotes a diverse group of dermatoses unified by the clinical feature of fine scaling of the skin. These conditions Pityriasis Rosea (PR), Pityriasis Versicolor (PV), Pityriasis Rubra Pilaris (PRP), and Pityriasis Lichenoides (PL) represent distinct pathophysiological entities driven by viral infection, fungal proliferation, genetic mutation, and immune-mediated mechanisms, respectively. This comprehensive review synthesizes current knowledge regarding the distinct etiology, pathomechanisms, clinical diagnostic challenges, and state-of-the-art therapeutic management for these four major scaling disorders.