12 Knuckle and Joint Appearance Changes Linked to Inflammatory Conditions

7. Nail Changes and Periungual Involvement

The nails and surrounding tissues frequently reflect systemic inflammatory processes, producing characteristic changes that can precede or accompany joint involvement in various arthritides. Nail pitting, characterized by small punctate depressions in the nail plate, occurs in approximately 80% of patients with psoriatic arthritis and represents one of the strongest predictors of joint involvement in psoriasis patients. Oil drop or salmon patch discoloration appears as yellowish-brown spots beneath the nail plate, creating a distinctive appearance that correlates with the severity of underlying joint disease. Nail fold capillaroscopy may reveal characteristic patterns of capillary dilation, dropout, and hemorrhages that indicate underlying vasculitis or connective tissue diseases. Periungual erythema and swelling often accompany active inflammatory arthritis, creating a red, puffy appearance around the nail beds that may be particularly pronounced during disease flares. Onycholysis, or separation of the nail plate from the nail bed, can occur in psoriatic arthritis and other inflammatory conditions, creating a characteristic lifting appearance at the free edge of the nail. These nail changes not only provide diagnostic information but also serve as easily monitored markers of disease activity and treatment response.