Isolated nail psoriasis: diagnostic challenges and therapeutic advances.

Isolated nail psoriasis, defined as psoriatic nail disease with no or little involvement of the skin, is a clinically significant yet frequently underrecognized condition. Its presentation often mimics other nail disorders such as onychomycosis or lichen planus which can lead to delayed diagnosis and inappropriate treatment. Patients may experience substantial functional impairment and psychosocial distress. This review highlights current knowledge of the epidemiology, clinical manifestations, and diagnostic challenges of isolated NP, with emphasis on populations where disease recognition is particularly difficult, including children, older adults, and patients with skin of color. Therapeutic options range from topical corticosteroids and vitamin D analogs to intralesional injections and systemic therapies. Despite recent therapeutic advances, response rates are often slower and less complete than in cutaneous psoriasis due to slow physiologic nail growth and treatment dissatisfaction is common. There is a need for standardized diagnostic criteria, validated outcome measures, and greater representation of diverse patient populations in clinical studies. Early identification and individualized treatment approaches are essential to reducing the burden of isolated NP on patient quality of life and long-term outcomes.