PMC8088535_01
(a) Non-contrast axial CT section demonstrates a large, well-defined, partially calcified midline mass that displaces each cerebral hemisphere laterally and displaces lateral ventricles posteriorly. There is no evidence of cerebral edema. (b) Non-contrast axial T2-weighted MRI displays heterogeneous internal texture of the mass. Myelinated cerebral white matter shows normal signal intensity with no evidence of cerebral edema. Clear, cerebral spinal fluid-containing cleavage plane (arrows) between medial surface of the right hemisphere and central mass confirms that the mass is extra-axial. (c and d) Contrast-enhanced T1-weighted MRI in coronal (c) and sagittal (d) planes shows heterogeneous enhancement along the surface and within the interstices of the tumor. There is marked compression of corpus callosum and lateral ventricles and a central vector of mass that displaces the brain downward through tentorial incisura and displaces cerebellar tonsils downward through foramen magnum. The nearly linear contour of the left side of mass and of the medial border of the left cerebral hemisphere again suggests that the mass arises from midline falx.
SNI-12-137-g001.jpg
PMC8088535_01_SNI-12-137-g001.jpg
F1
The initial non-contrast computed tomogram of the head showed a large, bifrontal, coarsely calcified extra-axial mass that scalloped the inner table of the skull and displaced the cerebral hemispheres circumferentially [Figure 1a]. The mass abutted on the right side of the superior sagittal sinus and right high convexity dura [Figure 1b-d], displaced both cerebral hemispheres inferolaterally, and displaced the corpus callosum and pericallosal vessels inferiorly.
H&E at x4 showing myxoid change and patchy necrosis.
SNI-12-137-g002.jpg
PMC8088535_01_SNI-12-137-g002.jpg
F2
This pathologist noted that although the diagnosis was difficult in this case, due to the presence of moderate cellularity, chondrocyte crowding, mild nuclear atypia, frequent binucleation, patchy necrosis, and myxoid change, a diagnosis of low-grade chondrosarcoma was most likely [Figures 2-4].
H&E at x10 showing focal increased cellularity.
SNI-12-137-g003.jpg
PMC8088535_01_SNI-12-137-g003.jpg
F3
This pathologist noted that although the diagnosis was difficult in this case, due to the presence of moderate cellularity, chondrocyte crowding, mild nuclear atypia, frequent binucleation, patchy necrosis, and myxoid change, a diagnosis of low-grade chondrosarcoma was most likely [Figures 2-4].
H&E at x40 showing a binucleate cell and mild atypia.
SNI-12-137-g004.jpg
PMC8088535_01_SNI-12-137-g004.jpg
F4
This pathologist noted that although the diagnosis was difficult in this case, due to the presence of moderate cellularity, chondrocyte crowding, mild nuclear atypia, frequent binucleation, patchy necrosis, and myxoid change, a diagnosis of low-grade chondrosarcoma was most likely [Figures 2-4].