Videocapillaroscopy in the Differential Diagnosis between Psoriasis and Seborrheic Dermatitis of the Scalp

Abstract

Background: Videocapillaroscopy (VCP) can be used to explore microcirculatory modifications in skin diseases. Psoriasis shows specific capillary alterations reflecting typical histopathological changes. Objective: To compare capillary morphology, distribution and density in psoriasis and seborrheic dermatitis of the scalp for differential diagnosis. Methods: VCP was performed on histology-confirmed scalp lesions of 30 patients with chronic plaque psoriasis, 30 age- and sex-matched patients with seborrheic dermatitis and 30 healthy subjects. The morphology, mean density per mm² and mean diameter of capillary loops was measured. Results: Scalp psoriasis exhibited homogeneously tortuous and dilated capillaries (bushy pattern), with a 73 ± 17 µm (mean ± standard deviation) diameter of capillary bushes. In contrast, scalp seborrheic dermatitis presented a multiform pattern, with mildly tortuous capillary loops and isolated dilated capillaries, but a substantial preservation of local microangioarchitecture. Mean diameter of capillary bush was significantly lower (27 ± 4 µm; p < 0.001) and similar to that of the scalp of healthy subjects (21 ± 5 µm). Capillary loop density was similar in patients with psoriasis (23 ± 5/mm²) seborrheic dermatitis (24 ± 2/mm²) and healthy scalp skin (24 ± 3/mm²). Conclusion: VCP could be a useful noninvasive approach for differentiating between psoriasis and seborrheic dermatitis, especially when the scalp is the only affected site.