Ultrastructural Study of Symmetrical Acral Keratoderma

Background: Symmetrical acral keratoderma is characterized by symmetrical brown hyperkeratotic patches on the acral extremities. However, no studies about its electron microscopic examination have been documented. Objective: Our study was performed to further characterize the histopathology of symmetrical acral keratoderma. Methods: A biopsy was taken from brown hyperkeratotic patches on the wrists. Investigative studies included light and electron microscopy. Results: Light microscopy showed epidermal basket-weave hyperkeratosis and acanthosis. Ultrastructurally, the epidermis was thickened by acanthosis and compact stratum corneum. The horny cell layers were remarkably thicker in clinical affected skin than in adjacent clinically unaffected and healthy skin. The keratin filaments were remarkably clumped or aggregated and irregularly distributed in the horny, spinous, granular and basal cell layers. The tonofilaments formed tight clumps or aggregated at the perinuclear cytoplasm. Conclusion: The main ultrastructural features of symmetrical acral keratoderma were epidermal hyperkeratosis and abnormalities of the keratin filaments and tonofilaments.