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Case Reports

Abstract

Epithelial sheath neuroma is a rare benign cutaneous lesion, first described by Requena et al in 2000. Fourteen prior cases of epithelial sheath neuroma have been described in the literature. We describe an additional case of a 77-year-old woman who presented with a one-month history of a pruritic indurated nodule on her back. The main clinical differential diagnosis included an irritated nevus or arthropod bite reaction. A shave biopsy specimen revealed a prominent epithelial sheath surrounding nerve bundles, consistent with a diagnosis of epithelial sheath neuroma. Epithelial sheath neuroma classically presents on the back as a firm erythematous to violaceous papule or nodule and is histologically characterized by enlarged nerve fibers surrounded by squamous epithelium in the dermis. The diagnosis of epithelial sheath neuroma can be challenging, given that the presence of squamous epithelium surrounding nerve cells is typically considered a feature of malignancy, especially cutaneous squamous cell carcinoma. Some have postulated that epithelial sheath neuroma may develop as a reactive hyperplasia of nerves and squamous epithelium in response to localized trauma and inflammation, such as secondary to rubbing. Hirano et al demonstrated a connection of an epithelial sheath neuroma to the overlying epidermis, supporting the hypothesis that the entity is a benign reactive hyperplasia and not a malignant process.