Histopathological and Immunohistochemical Differentiation between Psoriasis and Seborrheic Dermatitis of the Scalp: Based on Langerin and CD1a / 대한피부과학회지

ABSTRACT

Background@#Psoriasis and seborrheic dermatitis are difficult to distinguish if the lesion is localized to the scalp. @*Objective@#To validify the use of langerin and CD1a as markers of Langerhans cells to distinguish scalp psoriasis from seborrheic dermatitis. @*Methods@#We retrospectively evaluated 25 seborrheic dermatitis cases and 17 psoriasis cases diagnosed at a tertiary medical center in Korea from 2010 to 2019. The histopathological features and expression of CD1a and langerin were analyzed by dermato-pathologists. @*Results@#Hyperkeratosis, parakeratosis, and the presence of neutrophils in the parakeratotic mound were observed more frequently in the psoriasis group than in the seborrheic dermatitis group (p=0.016, p=0.027, and p=0.021, respectively). Other features examined did not show statistically significant differences. Dermal expression of langerin occurred more frequently in the psoriasis group than in the seborrheic dermatitis group (76.5% vs. 36.0%, p=0.010). Additionally, stronger CD1a dermal expression was observed in the psoriasis group than in the seborrheic dermatitis group (p=0.049), although the difference in overall dermal CD1a expression regardless of strength was not significant. In contrast, the epidermal expressions of CD1a and langerin did not show significant differences. Similarly, the follicular expressions of CD1a and langerin did not demonstrate significant differences. @*Conclusion@#In this retrospective study, histopathological findings that favored psoriasis over seborrheic dermatitis included hyperkeratosis, parakeratosis, and the presence of neutrophils in the parakeratotic mound. The use of Langerhans cells, CD1a, and langerin as markers could help distinguish scalp psoriasis from seborrheic dermatitis.