giovedì 25 febbraio 2010
There is a contrast enhancing extramedullary, intradural lesion at T6.
- Drop metastases
- Arachnoid cyst
Diagnosis: Spinal meningioma
Meningiomas are dural based, benign, slow growing tumors. They are usually solitary lesions and are 8 times more likely to occur in the brain than the spinal cord. When in the spinal cord, the thoracic spine is affected 80% of the time. On pathology, meningiomas are usually firm, round and well demarcated. Meningiomas have a peak incidence in the 5th and 6th decades of life. Presenting symptoms are usually due to mass effect the tumor has on adjacent neural tissue and can include pain, motor or sensory deficits.
Meningiomas are usually WHO grade I tumors (95%) and treated with surgical excision. In this case, the patient presented with back pain. She subsequently underwent resection of her tumor without recurrence.
Meningiomas are well circumscribed, strongly enhancing lesions. On non-enhanced CT, meningiomas are difficult to recognize and usually isodense to mildly hyper dense when compared to surrounding brain parenchyma. With contrast, meningiomas enhance homogeneously. On T1 and T2 weighted images, meningiomas are Iso intense in relation to the spinal cord. Some meningiomas are well vascularized and may demonstrate flow voids on T2 images. Meningiomas have well defined borders and do not invade adjacent neural tissue.
In this case, there is a solitary, intradural, extramedullary, homogeneously enhancing lesion in the mid-thoracic spinal cord. In an older female patient, meningioma is the likely diagnosis. Other intradural, extramedullary lesions include schwannoma, drop metastases, epidermoid, arachnoid cyst, and paraganglioma.
Schwannomas are nerve sheath tumors and have imaging characteristics similar to meningiomas. They usually occur in younger patients and can have a dumbbell shape as the tumor encases the nerve root across the neural foramen. In drop metastases, multiple contrast enhancing lesions are seen in the cord. Arachnoid cysts can cause mass effect similar to meningiomas, but are fluid filled structures that demonstrate no contrast enhancement. Epidermoid cysts are lobulated structures that minimally enhance and rarely occur in the spine. Paragangliomas rarely occur in the spine and occur in the cauda equina when they do.