PMC6028611_01
Sagittal, contrast-enhanced T1-weighted MR-image showing a mass (7 x 8 x 15 mm, height x depth x width) with peripheral contrast-uptake that was later identified as a low-grade chondrosarcoma. This mass was attached to the clivus and was located in close proximity to the medulla oblongata. Note that this MR-image was taken on day 2 and remained stationary over the course of the next 2 months.
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F1
T2-hyperintense intra-axial lesion (Figure 1) in the medulla oblongata (16 x 5 x 4 mm, height x depth x width) and a contrast-enhancing extra-axial lesion at the caudal part of the clivus (7 x 8 x 15 mm) were noted (Figure 2). There were no signs of acute ischemia [diffusion-weighed imaging (DWI) negative, no decrease in apparent diffusion coefficient (ADC)] or bleeding (susceptibility weighted imaging (SWI) negative). Repeated MRI (day 10) showed peripheral contrast-enhancement of the cystic lesion (25 x 11 x 9 mm) and progressive perifocal edema (Figure 1), whereas 5 days later (day 15) slight regression of the cystic lesion (22 x 6 x 6 mm) was noted.
Axial (top row) and sagittal (bottom row) MR-images of the intra-axial cystic lesion (indicated by the white solid arrows) located in the left part of the medulla oblongata over the course of 2 months. MR-images were obtained on day 2, 6, 7, 10, 15, 24, and 62 after symptom onset as indicated on the single MR-images. Whenever available, T1-weighted contrast-enhanced MR-images were selected for both axial and sagittal images [day 2, 6, 10, 15, 62 (only sagittal image)]. For the other MR-sessions, either T2-weighted (day 7) or gradient-echo T1-weighted [day 24 and 62 (only axial image)] MR-images were selected. Over the course of disease growth [from 16 x 5 x 4 mm on day 2-25 x 11 x 9mm on day 10 (height x depth x width)] and contrast-enhancement (first noted on day 6) of the cystic lesion can be depicted. After treatment initiation with dexamethasone (day 9) and surgical preparation of the solid lesion (day 15), the size of the cystic lesion decreased continuously and could not be detected any more on day 62.
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F2
T2-hyperintense intra-axial lesion (Figure 1) in the medulla oblongata (16 x 5 x 4 mm, height x depth x width) and a contrast-enhancing extra-axial lesion at the caudal part of the clivus (7 x 8 x 15 mm) were noted (Figure 2). There were no signs of acute ischemia [diffusion-weighed imaging (DWI) negative, no decrease in apparent diffusion coefficient (ADC)] or bleeding (susceptibility weighted imaging (SWI) negative).
Intraoperative view on the left inferior cerebellopontine angle (day 15). The bulging of the vascularized dura over the tumor can be seen and the lower cranial nerves are displaced. The posterior inferior cerebellar artery (PICA) is seen on the inferior aspect.
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F3
Intraoperatively, the two lesions seemed to be connected and the clival lesion was tightly adherent to the dura mater (Figure 3), which made it very difficult to explore the lesion in the medulla oblongata.