Broadening the Anatomic Landscape of Sclerosing Perineurioma: A Series of 5 Cases in Nonacral Sites.

Sclerosing perineurioma is a rare perineurioma variant thought to occur almost exclusively in digits and palms, predominantly in young adult men. It clinically presents as a solitary slow-growing nodule, sometimes associated with prior trauma. Since 01/01/2000, our institution has received 5 cases in consultation of sclerosing perineurioma presenting in atypical locations. Four of 5 patients were women. The median age at presentation was 45 years (range, 31-62 years). Sites included dorsal tongue, anterior neck, mid upper back, forearm, and proximal anterior thigh. Complete clinical histories were not available, although lesions were reported as subcentimeter nodules with at least 1 suspected to have formed after trauma. Histologically, all lesions were circumscribed to dermal/submucosal tumors. Some extended into subcutaneous fat. The neoplasms were composed of an admixture of bland spindled to epithelioid cells with uniform, wavy, thin-to-oval nuclei forming linear cords to whorled sheets in an extensively hyalinized stroma. Mitotic activity was inconspicuous. All tumors expressed epithelial membrane antigen and were negative for S100 protein. All cases stained for CD34 were positive (3/3). This series highlights a broader clinical presentation of sclerosing perineurioma than previously recognized. Acknowledgment of this anatomic variability should provide confidence to dermatopathologists faced with similar cases.