Perineuriomatous Nevus: A New Case Presentation With a Brief Review of the Literature

Perineuriomatous nevus (PN) is a rare variant of neurotized spindle-cell melanocytic nevus, first described in 2011, characterized by the expression of perineurioma markers such as epithelial membrane antigen and CD34 in a distinctive fingerprint-like pattern. Although PN is uncommon and not fully understood in terms of pathogenesis, recent studies have explored its definition, etiology, diagnosis, and differential diagnosis, particularly distinguishing it from benign and malignant entities such as neurocristic hamartoma and desmoplastic melanoma. Accurate diagnosis requires thorough morphologic and immunohistochemical analysis. This case report describes a PN in a 29-year-old woman with a pigmented nodule on her scapula, emphasizing histopathologic and immunohistochemical findings consistent with the literature. The lesion exhibited a biphasic structure, with a conventional nevoid component transitioning into a spindle cell population, showing epithelial membrane antigen and CD34 positivity in the spindle cells, while SRY-box transcription factor 10 and S-100 were positive in the nevoid cells. This case adds to the limited number of reported cases, helping to refine the diagnostic criteria for PN and its differentiation from other similar lesions.