Is there a role for conventional MRI and MR diffusion-weighted imaging for distinction of skull base chordoma and chondrosarcoma?

BACKGROUND: Chordoma and chondrosarcoma are locally invasive skull base tumors with similar clinical symptoms and anatomic imaging features as reported in the literature. PURPOSE: To determine differentiation of chordoma and chondrosarcoma of the skull base with conventional magnetic resonance imaging (cMRI) and diffusion-weighted MR imaging (DWI) in comparison to histopathological diagnosis. MATERIAL AND METHODS: This retrospective study comprised 96 (chordoma, n = 64; chondrosarcoma, n = 32) patients with skull base tumors referred to the Paul Scherrer Institute (PSI) for proton therapy. cMRI signal intensities of all tumors were investigated. In addition, median apparent diffusion coefficient (ADC) values were measured in a subgroup of 19 patients (chordoma, n = 11; chondrosarcoma, n = 8). RESULTS: The majority 81.2% (26/32) of chondrosarcomas displayed an off-midline growth pattern, 18.8% (6/32) showed clival invasion, 18.8% (6/32) were located more centrally. Only 4.7% (3/64) of chordomas revealed a lateral clival origin. Using cMRI no significant differences in MR signal intensities were observed in contrast to significantly different ADC values (subgroup of 19/96 patients examined by DWI), with the highest mean value of 2017.2 × 10(-6 )mm(2)/s (SD, 139.9( )mm(2)/s) for chondrosarcoma and significantly lower value of 1263.5 × 10(-6 )mm(2)/s (SD, 100.2 × 10(-6 )mm(2)/s) for chordoma (P = 0.001/median test). CONCLUSION: An off-midline growth pattern can differentiate chondrosarcoma from chordoma on cMRI in a majority of patients. Additional DWI is a promising tool for the differentiation of these skull base tumors.

Fanconi's syndrome, acute renal failure, and tonsil ulcerations after colloidal bismuth subcitrate intoxication.

A 22-year-old woman ingested 5.4 g of colloidal bismuth subcitrate (CBS) in a suicide attempt. After ingestion, she presented with Fanconi's syndrome and acute renal failure to our unit. On the third day after ingestion, she was anuric. Ulcerations of both tonsils were observed 8 days after intoxication. Sodium-2,3-dimercapto-1-propanesulfonate (DMPS) is shown to be an effective chelating agent of heavy metal intoxications, but it has only a small effect on elimination of bismuth salts in patients with renal insufficiency without hemodialysis. In our case, we initiated hemodialysis and intravenous treatment with DMPS 60 hours after intoxication. By repeated measurements of bismuth concentrations in serum and dialyzed fluid, we showed its successful elimination. Serum bismuth level decreased from 640 microg/L to 15 microg/L within 6 days. With elimination of bismuth, renal function improved, and tonsil ulcerations healed. Hemodialysis was discontinued on day 14. Follow-up examination 6 weeks later showed normal renal function. Clinicians should be aware that acute renal failure and tonsil ulcerations can occur after CBS intoxication. Generally, acute renal failure caused by CBS intoxication is reversible. Treatment with the chelating agent DMPS in combination with hemodialysis is highly effective in reducing the serum bismuth level in patients with acute renal failure.