Exploring Rare and Atypical Forms of Psoriasis: A Narrative Review

Psoriasis is a chronic immune-mediated inflammatory dermatosis characterized by marked clinical heterogeneity. Although plaque psoriasis represents the most common phenotype, several uncommon and atypical variants may pose considerable diagnostic challenges because of their unusual morphology, distribution, and clinicopathological presentation. Early recognition of these rare forms is essential to avoid misdiagnosis and inappropriate management. This narrative review summarizes the current evidence regarding selected atypical variants of psoriasis, including psoriasis gyrata, linear psoriasis, follicular psoriasis, psoriatic onycho-pachydermo-periostitis, psoriatic neurodermatitis, interdigital psoriasis, parakeratosis pustulosa, psoriasis of the lips, psoriasiform acral dermatitis, psoriasis dermatitis, and extreme hyperkeratotic forms. For each entity, we discuss epidemiology, clinical presentation, dermoscopic and histopathological findings, differential diagnosis, pathophysiological hypotheses, and therapeutic considerations. Particular attention is given to distinguishing these entities from inflammatory, infectious, and neoplastic mimickers. The integration of clinical evaluation with dermoscopy and histopathological examination remains crucial in challenging cases. Awareness of these uncommon variants may improve diagnostic accuracy and facilitate timely therapeutic intervention.