Combined oligodendroglioma/pleomorphic xanthoastrocytoma: A probable collision tumor: Case report

OBJECTIVE AND IMPORTANCE: We report the first case of combined oligodendrog lioma and pleomorphic xanthoastrocytoma. CLINICAL PRESENTATION: A female college student and competitive crosscountr y runner presented to the Mayo Clinic at age 18 years with complaints of pr ogressive headache and visual disturbances. Neuroimaging revealed a heavily calcified left parieto-occipital mass with focal enhancement and remodelin g of the overlying calvarium. INTERVENTION: A histological examination of the nearly gross total resectio n specimen disclosed a low-grade oligodendroglioma discretely abutting a su perficially situated focus of pleomorphic xanthoastrocytoma. Ten months the reafter, a recurrence was suspected on the basis of the detection of a new focus of nodular enhancement. This lesion stabilized after radiation therap y, and the patient is well, without apparent residual disease 2.8 years aft er surgery. CONCLUSION: This unique neoplasm is presumed to represent a collision tumor , its biological behavior being similar to that of oligodendroglioma alone. However, the possibility of an unusual, mixed oligoastrocytoma with pleomo rphic xanthoastrocytoma as the astrocytic component cannot be excluded enti rely. Potentially, both components have the capacity for recurrence and ana plastic transformation.