Atlanto-occipital Dissociation in the Setting of Relatively Normal Radiologic Findings.

BACKGROUND: Craniocervical junction (CCJ) dislocations are often fatal. Atlanto-occipital dissociation can be challenging to diagnose, especially in patients who present with absent or subtle radiologic signs. CASE DESCRIPTION: A neurologically intact 37-year-old patient presented to the hospital following a high-speed motor vehicle accident. Initial computed tomography scans showed normal CCJ anatomy, but magnetic resonance imaging (MRI) of the CCJ was performed to further evaluate perimesencephalic subarachnoid hemorrhage. MRI revealed partial disruption of the anterior atlantoaxial membrane and tectorial membrane as well as complete disruption of the posterior atlanto-occipital membrane, ligamentum flavum, and apical ligament, signifying atlanto-occipital dissociation. Halo spinal immobilization was performed in preparation for stabilization with posterior occipitocervical fusion; however, the CCJ distracted widely during surgery owing to the accident-related dislocation, signifying an unstable fracture. Posterolateral fusion was performed, and the distraction injury was corrected via posterior surgical instrumentation. CONCLUSIONS: Normal occiput-C1 craniometric parameters in the setting of unexplained perimesencephalic subarachnoid hemorrhage does not eliminate the possibility of missed or delayed diagnosis of traumatic atlanto-occipital dissociation injuries. Cervical MRI without contrast should be considered in patients with vertebral artery dissection or perimesencephalic subarachnoid hemorrhage after a blunt injury with neck pain. When MRI shows evidence of disruption of ≥2 atlanto-occipital ligaments, surgical stabilization should be considered, as these are clinically very unstable injuries.

An association of peripheral nerve sheath tumors and lipomas.

BACKGROUND: We noticed the coexistence of peripheral nerve sheath tumors (PNST) with lipomas within a subgroup of our patients. Given the prevalence of lipomas in the general population, we sought to investigate the extent of coexistence of the two entities aiming at uncovering any plausible association between both. METHODS: A retrospective review of all peripheral nerve sheath tumors (sporadic and syndromic forms) treated by a single surgeon between January 2009 and August 2015 was done. We recorded demographics (i.e., gender, age at diagnosis, imaging information, time to diagnosis) in addition to the method of diagnosis, subtype, number and location of lipomas, if present. RESULTS: Over 6 years, 309 patients with PNST were operated/evaluated. These included 141 sporadic (schwannomas, neurofibromas) and 168 syndromic (neurofibromatosis type 1 and 2 and schwannomatosis). We found 32 patients [10.3%, 95% confidence interval (CI) = 7.43%-14.3%] with coexistent lipomas, some of whom also had a family member with lipoma (n = 3). Of these 26 had schwannomas, 3 had neurofibromas and 3 lacked definitive PNST histopathological diagnosis. Fourteen percent of patients with schwannomas and 2.9% of patients with neurofibromas had coexisting lipomas. CONCLUSION: We believe there is an increased association of peripheral nerve tumors and lipomas overall.

Nerve-Adherent Giant Cell Tumors of Tendon Sheath: A New Presentation.

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. CASE DESCRIPTIONS: 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. CONCLUSION: 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.

The coexistence of peripheral nerve sheath tumors and vitiligo: more than coincidence?

Neurocristopathies arise from abnormal migration, differentiation, or proliferation of neural crest derivatives, leading to diverse clinical and pathological features. They are classified into dysgenetic or neoplastic, and can affect single or multiple sites (simple versus complex). Examples include congenital melanocytic nevi, neuroblastoma, Hirshsprung's disease, Waardenburg's syndrome, neurofibromatosis (NF) 1 and multiple endocrine neoplasia (MEN) 2A and 2B. We report two cases of peripheral nerve sheath tumors associated with vitiligo and discuss the possible implicated embryologic, genetic and molecular mechanisms. To our knowledge, we also report the first case of de novo malignant peripheral nerve sheath tumor (MPNST) associated with vitiligo.