A rare tentorial mesenchymal chondrosarcoma in posterior cranial fossa: case report.

Intracranial extraskeletal mesenchymal chondrosarcoma is a very rare malignant tumor with predilection site of frontoparietal falx cerebri. Only few cases of mesenchymal chondrosarcoma in posterior cranial fossa are reported. Here, we report a 23-year-old young man with a dura-attached mass in left posterior cranial fossa misdiagnosed as a tentorial meningioma preoperatively. According to the following operation, the lesion was confirmed as mesenchymal chondrosarcoma surgically and pathologically. On MRI, the tumor was characterized by lobulated soft-tissue mass with dura-attached base, patchy calcifications and heterogeneous signal intensities. On contrast-enhanced MRI, it was well-defined, with marked enhancement. We consider that these imaging features above might remind us to consider the diagnosis of mesenchymal chondrosarcoma in posterior cranial fossa. The postoperative treatment of radiotherapy is still controversial. As for our case, according to the 24 months follow-up after postoperative γ-knife, our patient shows an optimistic prognosis so far.