PMC4838752_01
A., Bone algorithm axial image from a noncontrast head CT demonstrates a lytic lesion within the left petrous apex (white arrow). B, C: Soft-algorithm axial images from a noncontrast head CT. B: Note low-attenuation, soft-tissue component of the mass within the left posterior fossa (black arrow), with peripheral areas of hemorrhage (white arrow). C: Note developing hydrocephalus secondary to mass effect on the fourth ventricle.
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Severe mass effect was noted in the posterior fossa, with obscuration of the fourth ventricle and developing hydrocephalus (Fig. 1).
A. Bone-algorithm, axial CT image demonstrates the typical chondroid calcifications associated with chondrosarcomas (black arrow). B. Soft-tissue-algorithm, axial CT image post contrast demonstrates mild heterogeneous enhancement (white arrowhead) of the mass, with notable extension into both the middle cranial fossa (white arrow) and posterior fossa (black arrow).
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Contrast-enhanced CT performed for stereotactic surgical guidance demonstrated mild contrast enhancement of the lesion (Fig. 2).
A. H&E section shows a conventional low-grade chondrosarcoma, WHO grade 1, with mildly atypical chondrocytes of various sizes and shapes in a prominent hyaline cartilage matrix (x400). B. In addition, there are extensive areas of acute and organizing hemorrhage with degenerating tumor cells (H&E, x200).
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Pathology later confirmed the presence of a low-grade chondrosarcoma, World Health Organization (WHO) Grade 1 with extensive hemorrhage (Fig. 3).