The Histopathologic Spectrum of Psoriasis

In the 2007 paper, the authors examined the histopathologic features of psoriasis, noting that these features can vary with the lesion's age and may include epidermal hyperplasia, elongation of rete ridges, dilated blood vessels, neutrophil infiltration, hypogranulosis, and increased keratinocyte mitosis. They discussed the high turnover of psoriatic lesions, different keratin expression, and variants like guttate and pustular psoriasis, which have unique clinical and histopathologic presentations. The paper highlighted that while psoriasis has characteristic histopathologic features, they may not always be present in biopsies, and regional variations like scalp psoriasis can cause hair loss due to telogen effluvium. It also detailed nail involvement in psoriasis, with up to 50% of patients with skin lesions having fingernail changes and up to 35% with toenail changes. The authors stressed the need for clinicopathologic correlation and additional stains for accurate diagnosis, as neutrophil presence and parakeratosis are highly indicative of psoriasis but not exclusive to it. The conclusion was that psoriasiform dermatoses are complex and may require multiple biopsies for a definitive diagnosis.