Background  Keratolysis exfoliativa (KE), also known as dyshidrosis lamellosa sicca, is a palmoplantar dermatosis characterized by air-filled blisters and collarette desquamation. It has been regarded as a subtype of dyshidrotic eczema, a fungal infection or a dermatophytid reaction. KE may also resemble acral peeling skin syndrome and localized epidermolysis bullosa simplex. Although KE is a common disorder, it is a rarely reported and is an under-recognized dermatosis.

Objectives  To delineate the characteristic features of KE.

Methods  We investigated the clinical, immunohistopathological, ultrastructural and molecular features of KE. Patients were included from the clinical records. Additional diagnostic research consisted of mutation analysis of the candidate genes TGM5, KRT5, KRT14, FLG, SPINK6 and SPINK9.

Results  A total of 24 patients with KE were identified, six with familial and 18 with sporadic KE. Lesions consisted of air-filled blisters only on palmoplantar skin, followed by collarette and lamellar peeling. Both light microscopy and electron microscopy showed cleavage and partially degraded corneodesmosomes within the stratum corneum, whereas immunofluorescence microscopy showed normal expression of corneodesmosomal components. No mutations were found in TGM5, KRT5/14 and SPINK6/9. There was no clear link with atopy or with FLG mutations.

Conclusions  Our study suggests premature corneodesmolysis as the main pathological mechanism of this palmoplantar skin disorder. We conclude that KE appears to be a distinct peeling entity.