Perineurioma can mimic liposarcoma
Mayo Clinic Proceedings flagged a pseudolipoblastic variant of perineurioma that can look like liposarcoma because it contains cells with fat‑like morphology (x.com). The note warned these unusual morphologic variants may be mistaken for malignant adipocytic tumors if diagnosis relies on morphology alone (x.com).
A rare benign nerve-sheath tumor can look like liposarcoma under the microscope, and Mayo Clinic Proceedings said that resemblance can mislead diagnosis. (mayoclinicproceedings.org) Perineurioma grows from perineurial cells, the thin layers that wrap and protect peripheral nerves, and Mayo Clinic lists it among benign peripheral nerve tumors. (mayoclinic.org) The confusing subtype is called pseudolipoblastic perineurioma. A 2016 Human Pathology report described 2 cases, in a 30-year-old man’s tongue and a 67-year-old woman’s triceps, with vacuolated cells that resembled lipoblasts, the fat-like cells pathologists often associate with liposarcoma. (pubmed.ncbi.nlm.nih.gov) That distinction changes the stakes. Perineurioma is generally classified as benign, while liposarcoma is a malignant adipocytic tumor, so the same slide can point to very different treatment conversations. (pathologyoutlines.com) The problem is that morphology alone can deceive. The 2016 paper said careful review plus immunohistochemical testing helped separate these lesions from liposarcoma by showing a perineurial profile rather than a fat-tumor profile. (sciencedirect.com) Those marker patterns are concrete: Pathology Outlines says soft-tissue perineurioma typically expresses epithelial membrane antigen, glucose transporter 1, and claudin-1, while lacking S100 protein, a pattern used in routine surgical pathology workups. (pathologyoutlines.com) The variant is also exceptionally uncommon. A 2024 case report called pseudolipoblastic perineurioma a very uncommon extraneural perineurioma variant with only a limited number of cases documented in the literature. (pmc.ncbi.nlm.nih.gov) More unusual presentations have kept turning up. A 2023 Journal of Neurosurgery: Case Lessons report described what the authors said was the first known pseudolipoblastic perineurioma affecting a nerve, in the sciatic nerve of a 52-year-old woman whose pain resolved after resection. (thejns.org) The practical message for pathologists is narrow but important: when a tumor has fat-like vacuolated cells, the slide may still represent a benign perineurioma, not a liposarcoma. (sciencedirect.com)
