The Sole Solution: Hyperkeratotic Eczema Mimicking Psoriasis Responds to Dupilumab

Summary: Background: Differentiating hyperkeratotic eczema from palmoplantar psoriasis is challenging due to overlapping clinical features, making histopathology crucial for accurate diagnosis.1,2 While dupilumab has shown efficacy in treating hand eczema, its use in treating isolated hyperkeratotic hand and foot eczema is underexplored. Here, we report a case of hyperkeratotic eczema with positive response to dupilumab. Case Presentation: A 69-year-old female with persistent rash of the hands and feet, originally treated as palmoplantar psoriasis, showed lack of response to risankizumab, light therapy, clobetasol, and topical terbinafine. Skin biopsy showed hyperkeratosis, psoriasiform hyperplasia with intact granular layer, and significant epidermal spongiosis. The superficial dermis showed a lymphocytic infiltrate without significant eosinophils and without prominent dilated papillary dermal vessels. These findings, along with clinical presentation, supported a diagnosis of hyperkeratotic eczema. The patient was started on dupilumab and showed near total resolution of her rash. Discussion: Hyperkeratotic eczema is a clinical eczema subtype with a largely unknown pathophysiology. A small case series evaluating dupilumab use for hyperkeratotic eczema found improvement in 2 out of 3 patients by 16 weeks.3 Our case highlights the role of histopathology in differentiating hyperkeratotic eczema from psoriasis and further supports the role of dupilumab in treating hyperkeratotic eczema.