title: Infiltrating retiform perineurioma: a case report.
abstract: Retiform perineurioma is a rare distinct histologic subtype of benign soft tissue perineurioma. We report 1 case of retiform perineurioma with a superficial invasion of the adjacent skeletal muscle. The patient was a 34-year-old woman with a neoplasm located between the deltoid muscle and the biceps. Histologically, the tumor was nonencapsulated, composed exclusively of perineurial cells without cytologic and tissue atypia. There were focal areas in which the neoplastic cells infiltrated the muscle tissue, widely separating the bundles. This case may represent a diagnostic pitfall as it can be confused with a malignant perineurioma.
authors.affiliation: Department of Pathology, Petrov's Institute of Oncology, 197758 Saint Petersburg, Russia.
authors.forename: Ksenia
authors.initials: K
authors.lastname: Shelekhova
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kazakov
authors.forename: Michal
authors.initials: M
authors.lastname: Michal
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D018482:Muscle, Skeletal / Q000473:pathology; D018317:Nerve Sheath Neoplasms / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000473:pathology*