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This report describes the MR and correlative imaging findings of four histologically proved cases of subacute necrotizing myelopathy in which there was no evidence of a spinal dural arteriovenous fistula. Subacute necrotizing myelopathy is characterized clinically by progressive motor and sensory deterioration, and pathologically by necrosis in the spinal cord. Initial MR imaging showed focal enlargement of the spinal cord and nonspecific T1 and T2 lengthening. Rimlike enhancement was demonstrated in one case. Clinically, steroid therapy failed in all four patients. Follow-up MR scans showed two slightly enlarged lesions, one stable thoracolumbar lesion, and atrophy of a cervical lesion. Open spinal cord biopsies revealed foci of necrosis and abnormal parenchymal vessels with thickened hyalinized walls. A prolonged course distinguishes subacute necrotizing myelopathy from acute transverse myelitis, but the clinical course and imaging appearance are similar to those of intramedullary tumor. Rimlike rather than solid contrast enhancement may be a distinguishing feature. In the absence of a demonstrable spinal dural arteriovenous fistula, the radiologic differentiation of subacute necrotizing myelopathy from tumor is probably impossible, and biopsy establishes the correct diagnosis.

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Five pathologically proved melanotic neuroectodermal tumors of infancy are reported. These rare neoplasms of infancy exhibit a distinct predilection for the maxillary bone. Three tumors originated in the maxilla, one in the calvaria, and one in the cerebellar vermis. Those occurring in bone did not metastasize but were locally invasive, as reflected in their radiologic appearance. Bone erosion, expansion, hyperostosis, and osteogenesis can occur in the same neoplasm and were appreciated best on CT. MR imaging showed the soft-tissue component and extent of the neoplasm better than CT did. The pathologic findings from all five cases (and one possibly related melanotic tumor of the face) revealed abundant melanin. MR imaging of two melanotic tumors showed isointense T1-weighted and slightly hyperintense T2-weighted signals. This appearance is contrary to that of most melanin-containing tumors, which exhibit enhanced T1 and T2 relaxation, and indicates that variables other than the absolute amount of melanin may determine the MR signal. Clinically, rapid neoplastic growth and excessive melanin production by the tumor cells caused facial disfigurement and visible blue black discoloration. All five melanotic neuroectodermal tumors were resected and the vermian tumor was also irradiated. Four of five children were well and free from disease 1 month to 7 years after resection. The calvarial tumor was incompletely resected and involved the underlying brain, eventually causing death. The clinical, radiologic, and pathologic features of melanotic neuroectodermal tumors of infancy are reviewed. Melanotic neuroectodermal tumors of infancy that involve bone can be diagnosed from the clinical and radiologic findings. Prompt diagnosis and surgical resection are essential for cure.

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The authors describe and discuss the safe percutaneous placement of an infracolic gastrojejunostomy catheter in a burn patient with no other access route for nutritional support.

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We present and discuss an unusual case of extensive abdominal plexiform neurofibromatosis that simulated pseudomyxoma peritonei on CT. Multiple low density subdiaphragmatic masses caused scalloped liver margins and thickening of the mantle, which displaced bowel loops centrally, suggesting the diagnosis of pseudomyxoma peritonei. However, open biopsy revealed plexiform neurofibromatosis.

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Gastric balloons have been used extensively as an adjunct to diet and behavioral modification in the treatment of exogenous obesity. Small bowel obstruction occurred in a 42-year-old female after her balloon migrated through the pyloric channel. The authors describe a simple method for percutaneous deflation which permitted the balloon to pass through the gastrointestinal tract thus relieving the obstruction.

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Unusual tubular calcification occurred in the nephrostomy tract of a 30-year-old male, 6 months after percutaneous nephrostolithotomy. To our knowledge, this phenomena has not been previously reported. The main radiologic differential diagnoses are focal dystrophic calcification and vascular calcification. The etiology is unknown but may have been related to the patients' tendency to form renal calculi. The temporal sequence of events and the location of the nephrostomy catheter which correlated with the calcification suggests the correct diagnosis.

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We report a case of pathologically proven metastatic trophoblastic neoplasm involving the adnexa which occurred after dilatation and curettage and chemotherapy. Duplex doppler ultrasound demonstrated increased vascularity in the adnexa. Angiography was sensitive but did not decisively distinguish between tumor in the adnexa and arteriovenous fistula in the uterus. In addition to abnormal vascularity, magnetic resonance also showed foci of abnormal signal in the adnexa not seen in the uterus and correctly suggested the presence of tumor.

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We report a case of post-traumatic lumbar arachnoid cyst, which enlarged the spinal canal and eroded the posterior elements. Computed tomographic myelography and magnetic resonance (MR) were complementary, and both correctly characterized the cystic nature of the lesion. Communication between the cyst and the subarachnoid space was demonstrated on CT myelography, which also clearly showed bone changes in the spinal canal. Continuity of the cyst with the spinal subarachnoid space was seen clearly on sagittal MR, and the MR signal characteristics of the cyst were identical with CSF.

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High resolution magnetic resonance (MR) imaging of three salivary gland tumors was performed at 1.5 T and compared with CT. Two of the three tumors were well seen on CT. However, one required CT sialography to separate tumor from the remaining parotid parenchyma, and, in the other, soft tissue invasion could not be excluded on the basis of CT. Magnetic resonance imaging demonstrated sharp tumor margins with no evidence of invasion. All three tumors were pathologically proven benign pleomorphic adenomas confirming the MR findings. On T2 weighted images, the two large adenomas demonstrated inhomogeneity that was not observed on CT.

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