Intraneural Perineurioma: A Systematic Review With Illustrative Cases

Abstract Context.—Intraneural perineurioma may be confused with other “onion bulb” Schwann cell entities (localized hypertrophic neuropathy, reactive/demyelinating processes, or inherited polyneuropathies of Charcot-Marie-Tooth/Dejerine Sottas) due to similar clinical, radiologic, and histologic features. Perineurial and Schwann cells can only be differentiated by ultrastructure and immunohistochemsitry. Objective.—To identify and summarize the clinicopathologic features of true cases of intraneural perineurioma from the English language literature. Data Sources.—A systematic review was performed on definitive intraneural perineuriomas identified through Medline. Baylor College of Medicine–affiliated hospitals' anatomic pathology databases yielded 2 illustrative intraneural perineurioma cases. Study Selection.—Intraneural perineurioma inclusion criteria consisted of characteristic histology and confirmation of perineurial cell lineage by either immunohistochemistry (epithelial membrane antigen positive, S...