Immunohistochemical differentiation of keratins and involucrin between palmar psoriasis, chronic hand eczema and hyperkeratotic hand eczema.

Background: Common hyperkeratotic palmar skin lesions include chronic hand eczema (CHE), hyperkeratotic hand eczema (HHE), palmar psoriasis (PP). However, clinically differentiating these disorders is often challenging.
Objectives: To compare the expressions of keratin (K) 5, K9, K14 and involucrin in palmar hyperkeratotic lesions (HHE, CHE and PP).
Materials and Methods: Immunohistochemical staining was performed on skin biopsy specimens obtained from the palms of patients clinically diagnosed with CHE, HHE and PP (n = 21, 24 and 18, respectively).
Results: K5 and K14 expression levels were higher in the spinous and granular layers of PP and HHE compared to CHE. Involucrin was expressed in the basal layer of PP and HHE but not in CHE. K9 expression was decreased in PP and HHE compared to CHE.
Conclusion: Keratin and involucrin expression in the epidermis are markers of keratinocyte differentiation. Expression levels of keratin and involucrin were similar between the HHE and PP groups, suggesting that HHE shares pathogenesis with PP rather than CHE.
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