Circumscribed palmo-plantar hypokeratosis: a disease of desquamation? Immunohistological study of five cases and literature review

Abstract

Background: Circumscribed palmoplantar hypokeratosis (CPH) is a recently recognized, rarely reported dermatosis that shows characteristic clinicopathological features; however, its pathogenesis remains unknown.

Objective: The aim of this study was to get further insight into the pathogenesis of CPH.

Methods: An immunohistological study was performed on five cases of CPH to investigate the expression of several epidermal proliferation and differentiation proteins, with emphasis on those involved in corneocyte desquamation [including corneodesmosin, kallikrein 5 and lympho-epithelial Kazal type inhibitor (LEKTI)].

Results: In three of five cases, a decreased expression of LEKTI, corneodesmosin and filaggrin was found, along with an increased expression of kallikrein 5 and keratin 6. The expression of several other antigens (including involucrin, Ki67, p63, CD138/syndecan I, EGF-R) did not present a consistently different pattern as compared with the unaffected epidermis.

Conclusion: The immunohistopathologic features of CPH suggest that an altered (accelerated) corneocyte desquamation process could be the main pathological mechanism underlying the development of lesions.