Extensive cartilaginous metaplasia of recurrent posterior fossa ependymoma: case report and review of the literature.

Cartilaginous metaplasia in ependymomas is extremely rare and only few cases have been reported in the literature. We describe a case of a 5-year-old patient with a 5th recurrence of 4th ventricle ependymoma. He was previously treated with 4 resections, chemotherapy and radiotherapy. Histopathology revealed well-differentiated chondroid tissue occupying almost the entire lesion. Near total resection was achieved for the 5th time, but the patient died 3 months later achieving a total survival of 48 months, the 3rd longest reported in literature. Multiple resections of tumour recurrence provided a new insight in this very rare tumour, as it gave us the opportunity to observe the progression of tumour aggressiveness from grade II to grade III and finally to chondroid metaplasia. Cartilaginous metaplasia in posterior fossa ependymomas is a very atypical and challenging tumour with poor overall prognosis.