title: Nerve-Adherent Giant Cell Tumors of Tendon Sheath: A New Presentation.
abstract: BACKGROUND
  Tenosynovial giant cell tumors are a group of slowly growing benign neoplasms of synovial membrane of joints, tendons, and bursae. The localized type or giant cell tumor of tendon sheath (GCTTS) is the extra-articular form of tenosynovial giant cell tumors. We describe two patients with a GCTTS, confirmed histologically at the time of surgical resection, that was adherent to peripheral nerves. Rare GCTTS can cause extrinsic compression of major nerves.
  
  
  METHODS
  The first patient was a 36-year-old man with a left wrist mass associated with pain and paresthesia in the radial three digits. On ultrasound and magnetic resonance imaging (MRI), the mass appeared arising from the left median nerve with a picture suggestive of an atypical neurogenic tumor; however, the possibility of GCTTS could not be excluded. Intraoperatively, the tumor was adherent to the median nerve without a connection to nearby intercarpal joints. The second patient was a 25-year-old woman with a history of malignant melanoma and an incidentally discovered mass on routine follow-up. MRI of the pelvis showed an ovoid mass related to the right sciatic nerve. The MRI picture was suggestive of a GCTTS, although a benign neurogenic tumor was favored given the anatomic relation to the sciatic nerve. Intraoperatively, the tumor appeared as a nodule implanted on the nerve, and it was easily peeled off.
  
  
  CONCLUSIONS
  We present a new, rare presentation of GCTTS adherent to peripheral nerves with extrinsic compression. We suggest either an implantation mechanism or an unrecognized extrasynovial origin for such tumors.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Elsherif
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Doris E
authors.initials: DE
authors.lastname: Wenger
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Vaubel
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA. Electronic address: spinner.robert@mayo.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D005260:Female; D005682:Gadolinium / Q000493:pharmacokinetics; D000070779:Giant Cell Tumor of Tendon Sheath / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D019635:Neurosurgical Procedures; D049268:Positron-Emission Tomography; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D005682:Gadolinium; C067980:CD68 antigen, human; D000097382:CD68 Molecule
keywords: Adherent; Extrasynovial; Giant cell tumor of tendon sheath; Implantation; Nerve compression; Peripheral nerves; Tenosynovial giant cell tumors