This patient has the classic features of psoriatic nail dystrophy with onycholysis (lifting of nail off the nail bed) that appears as areas of white nail at the lateral edges of the nail plate. This patient also has pitting of the nails, which manifests as small indentations on the surface of the nail plate. Lastly this patient also has “oil spots,” which are the areas of yellow-tan discoloration at the distal end of the nail plate. Psoriasis most commonly presents as long-standing, discrete, erythematous plaques with silvery-white scale. Other patterns include inverse (intertriginous), guttate, pustular, and erythrodermic types. Nail changes occur in about 75% of patients with psoriasis. The most common psoriatic nail abnormality is subungual hyperkeratosis. Pitting and ridging are more common on fingernails as compared with toenails. The “oil drop” sign, which is yellow-tan discoloration, is another typical manifestation. Multiple nails are generally affected, both on the hands and feet. Over time, a significant amount of nail dystrophy can occur, and the changes may be indistinguishable from onychomycosis. Patients with psoriatic nail dystrophy are more often affected by psoriatic arthritis, but nail findings do not necessarily correlate with the severity of disease.
Candidal infection can cause intertrigo, recognized as pink-red patches with satellite lesions in skin folds but is an uncommon cause of nail dystrophy.
The eczematous dermatoses are a diverse group of skin disorders that share clinical features of itching and a red, scaly, vesicular-to-crusted rash. Eczema can cause changes in the nail plate (nail dystrophy), but it is secondary to inflammation of the nearby skin of the proximal and lateral nail folds, which is not present in this patient.
Tinea manuum is a dermatophyte infection involving the hand. Dermatophytes are the most common fungi that infect skin. Tinea manuum characteristically involves only one hand (and two feet). The findings are characterized by a dry scale, and if chronic, the nails can be involved. The diagnosis of tinea manuum is unlikely if the feet are not involved.
