Korean J Dermatol.  2021 Sep;59(8):634-639.

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

• Yoon JH
• Park HR
• Park EJ
• Kim KJ
• Kim KH

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.

Keyword

CD1a; CD207 protein; Langerhans cells; Psoriasis; Seborrheic dermatitis