title: Giant plexiform schwannoma: a report of two cases with soft tissue and visceral involvement.
abstract: We report two cases of massive, solitary, plexiform schwannoma. One was a 9-cm subcutaneous lesion on the hip of a 72-year-old man who had become aware of the slow-growing tumor 50 years earlier; the other is the first reported plexiform schwannoma to arise in a visceral organ: it arose in the ascending colon of a 54-year-old man and exhibited a dumbbell configuration with submucosal and subserosal components. Neither patient had neurofibromatosis or schwannomatosis. Both tumors were well-circumscribed and multinodular, and both showed a plexiform architecture. Microscopically, the nodules were composed primarily of Antoni A tissue, replete with nuclear palisading and Verocay bodies. Examination by immunohistochemistry and electron microscopy demonstrated the features of well-differentiated Schwann cells; nodules were surrounded by attenuated, residual perineurium. Both patients followed a benign clinical course, without recurrence or metastasis. Neither the large tumor size nor the unusual locations affected the biologic behavior of these neoplasms. A massive plexiform schwannoma must be distinguished from a malignant peripheral nerve sheath tumor and from a plexiform neurofibroma, a tumor prone to malignant transformation.
authors.affiliation: First Department of Pathology, University of Tokushima School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hirose
authors.forename: B W
authors.initials: BW
authors.lastname: Scheithauer
authors.forename: T
authors.initials: T
authors.lastname: Sano
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D003110:Colonic Neoplasms / Q000737:chemistry / Q000473:pathology*; D006615:Hip; D006801:Humans; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000737:chemistry / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000737:chemistry / Q000473:pathology*; D014781:Viscera
chemical_list: D014408:Biomarkers, Tumor