Keratoelastoidosis Marginalis of the Hands: A Distinct Form of Palmoplantar Keratoderma.

Keratoelastoidosis marginalis of the hands (KEMH) is an acquired form of marginal papular keratoderma, characterized by thickened keratotic plaques predominantly affecting the lateral side of the index finger and the medial side of the thumb. It is often associated with chronic sun exposure and trauma, usually affecting older individuals. Due to clinical similarities with other palmoplantar keratodermas, differential diagnosis is essential for effective treatment management. Although clinical information is often sufficient for differentiation, a skin biopsy can provide valuable diagnostic clues. We report the case of a 63-year-old male patient who presented with rough linear hyperkeratotic lesions on the lateral and medial margins involving the first and second fingers of both hands, which had developed over a period of three years. Skin biopsy revealed orthohyperkeratosis with an underlying epidermis of normal thickness, with no features of actinic keratosis. In the dermis, thickened elastic fibers and degenerated collagen bundles were haphazardly distributed. Based on clinicopathological findings, a diagnosis of KEMH was made. As limited information is available in the literature, we aim to expand the current understanding of KEMH by emphasizing crucial aspects of its pathogenesis, histological characteristics, and main differential diagnoses.