Psoriasis, known for its inflammatory skin lesions and joint involvement, lacks clear diagnostic criteria and a unified classification system. Attempts to categorize it have considered factors like age of onset, disease severity, and morphology, yielding subtypes such as plaque, guttate, pustular, and erythrodermic psoriasis. Diagnosis primarily hinges on recognizing patterns through evaluating skin lesions and joints, occasionally supplemented by histopathological examination.

As a leading autoimmune disease affecting 2% to 5% of the global population, psoriasis poses significant health and economic challenges. While its exact cause remains unclear, it’s believed to stem from a complex interaction of genetics, environment, and immune dysfunction. Skilled clinicians can identify psoriasis and its subtypes based on distinct morphological features, bypassing the need for histopathological examination or specific blood tests. Despite lacking clear diagnostic criteria, psoriasis is classified based on clinical characteristics and phenotypes.

Reference: Raychaudhuri SK, Maverakis E, Raychaudhuri SP. Diagnosis and classification of psoriasis. Autoimmun Rev. 2014 Apr-May;13(4-5):490-5. doi: 10.1016/j.autrev.2014.01.008. Epub 2014 Jan 13. PMID: 24434359.