ABSTRACT
The lesions of seborrheic dermatitis may closely resemble clinically those of psoriasis. Their distribution is generally different, but when lesions are confined to the scalp and are long standing, even histology may hardly differentiate the two conditions. Distinction of seborrheic dermatitis from psoriasis is obviously relevant for the long-term prognosis, but it may be particularly important in patients with arthritis symptoms. In fact, the presence of skin psoriasis is the most relevant criteria for the diagnosis of psoriatic arthritis, and deciding whether erythematous scaly plaques on the scalp are psoriasis or seborrheic dermatitis may change the interpretation of the rheumatic symptoms. An important difference between psoriasis and seborrheic dermatitis could be the microvasculature changes, which are constantly present and characteristic in psoriasis.(5, 6)
In a recent study we employed videocapillaroscopy (VCP) to compare capillary morphology, distribution, and density in psoriasis and seborrheic dermatitis of the scalp to use for differential diagnosis.(1) VCP was performed using an optical probe (Videocap 200R DS Medica, Milano, Italy) on histologyconfirmed scalp lesions of 30 patients with chronic plaque psoriasis, 30 patients with seborrheic dermatitis, and 30 healthy subjects.
