Hyperkeratotic hand eczema: Eczema or not?

Area of Science:

• Dermatology
• Molecular Biology
• Pathophysiology

Background:

• Hyperkeratotic hand eczema (HHE) is a common clinical subtype of hand eczema.
• The underlying pathophysiology of HHE remains largely unknown.

Purpose of the Study:

• To investigate the histopathology of HHE.
• To examine the expression of keratins (K), epidermal barrier proteins, and adhesion molecules in HHE.
• To screen for mutations in genes associated with palmoplantar keratoderma.

Main Methods:

• Palmar skin biopsies from HHE patients and healthy controls were analyzed.
• Immunofluorescence staining was used to assess protein expression.
• Genetic screening of 135 candidate genes was performed.

Main Results:

• Significant reduction in K9 and K14 expression in lesional skin.
• Upregulation of K5, K6, K16, and K17 in lesional skin compared to controls.
• Involucrin and loricrin showed altered extracellular staining patterns; filaggrin expression was unchanged. No mutations were identified.

Conclusions:

• The current classification of HHE may need re-evaluation.
• Observed protein expression patterns, particularly filaggrin and involucrin, do not align with atopic eczema pathogenesis.
• Altered keratin expression (K6, K16, K17, K9, K14) likely contributes to HHE pathogenesis.