Resolution of intraspinal retro-odontoid cyst associated with os odontoideum after posterior fixation.

STUDY DESIGN: A case report and review of previous literature. OBJECTIVES: To describe the diagnosis and successful treatment of an intraspinal retro-odontoid cyst associated with an os odontoideum. SUMMARY OF BACKGROUND DATA: Retro-odontoid cysts associated with atlantoaxial instability are extremely rare. Direct excision of the cysts has commonly been performed for the surgical treatment of myelopathy. METHODS: A retro-odontoid cyst in a 58-year-old woman with os odontoideum was treated surgically by posterior fixation between C1 and C3 without resection of the retro-odontoid mass. The patient's history, clinical examination, imaging findings, and treatment are reported. RESULTS: The patient experienced walking difficulty, numbness in the upper and lower limbs, and hypesthesia in both hands. Congenital C2/3 fusion and atlantoaxial instability associated with an os odontoideum were found in the radiographs. Magnetic resonance imaging detected a round retro-odontoid mass, which compressed the spinal cord. The mass showed uniform low intensity on T1-weighted images and uniform high signal intensity on T2-weighted images. Gadolinium-diethylenetriaminepenta-acetic acid-enhanced T1-weighted images showed rim enhancement of the mass with no internal enhancement. Three months after the operation, the mass was no longer visible in a magnetic resonance imaging examination and the patient completely recovered motor function in her extremities. CONCLUSIONS: Posterior fixation without resection was successfully used to eliminate a retro-odontoid cyst associated with atlantoaxial instability.

A simple bone cyst located in the pedicle of the lumbar vertebra.

A simple bone cyst located in the spine is rare. In the current work, we have documented the first case of a simple bone cyst located in the pedicle of the lumbar vertebra. The patient was a 50-year-old woman with low back pain. Radiographs of the lumbar region of the spine showed a well circumscribed radiolucent lesion with surrounding bone sclerosis in the right pedicle of L3. Computed tomography (CT) showed that the right pedicle was completely occupied by the cyst and slightly expanded. The cystic lesion extended to both the vertebral body and the lamina. T1-weighted magnetic resonance imaging (MRI) showed uniform low intensity, and T2-weighted MRI showed uniform very high intensity. Signal enhancement by gadolinium diethylenetriaminepenta-acetic acid was not observed in the lesion. During the operation, the cavity of the cyst was filled with 2 mL of serosanguinous fluid. Subsequent histologic examination showed a thin layer of connective tissue in the inner surface of the cyst.

Dumbbell-shaped chondrosarcoma that primarily developed in the cervical spine: a case report.

There have been few reports describing dumbbell chondrosarcomas that primarily developed in the cervical spine; and among these cases even fewer can easily be diagnosed as chondrosarcoma. We report a 58-year-old man who complained of right cervical pain and swallowing difficulty without a particularly apparent cause. Magnetic resonance imaging (MRI) and computed radiography (CT) suggested a diagnosis of dumbbell tumor. 99mTc HMDP bone scintigraphy and 201Tl scintigraphy were negative, and surgery was performed assuming the presence of a neurogenic tumor. Intraoperative histopathological examination showed similar results. The postoperative histopathological diagnosis, however, was chondrosarcoma (grade II). Retrospective discussion regarding the diagnosis of the patient revealed that gadolinium-enhanced MRI was not appropriate for a precise diagnosis and that CT was more effective. We have thus experienced a patient with a rare dumbbell chondrosarcoma that primarily developed in the cervical spine for which a preoperative diagnosis was difficult.