Posterior fossa recurrence of WHO grade II and III supratentorial gliomas.

Objective/background: Posterior fossa (PF) recurrences of supratentorial (ST) World Health Organization (WHO) grade II and III gliomas are thought to be rare and to have grim prognoses.
Methods: This study entailed searching through our database and reviewing the records of patients with grade II and III ST gliomas who developed PF recurrence with no overt secondary gliomatosis or leptomeningeal spread.
Results: Of 2266 grade II and III gliomas, 14 fulfilled the inclusion criteria: 5 oligodendrogliomas (O; 1 OII, 4 OIII); 7 astrocytomas (A; 4 AII, 3 AIII); and 2 oligoastrocytomas (OA; both OAIII). The male/female gender ratio was 10/4, and median age at recurrence was 43 years. Two groups were identified. In one group (n=8; 1 AII, 3 AIII, 2 OAIII, 2 OIII), a rapidly growing contrast-enhancing PF mass (6/8) was associated with ST progression, and median survival time after detection was only 6.5 months despite radiotherapy and/or chemotherapy. In the second group (n=6; 3 AII, 1 OII, and 2 OIII), a non-contrast-enhancing (5/6), asymptomatic (5/6), slow-growing PF mass remained isolated, and treatment with radio- or chemotherapy produced objective responses in three patients and durable stabilization in the remaining three. After a median follow-up of 63months, only one patient died due to delayed recurrence of the ST lesion, while the remaining five patients are still alive.
Conclusion: Non-contiguous PF relapses of ST grade II and III gliomas are rare. A high-grade ST tumor that is concomitantly progressing appears to be a predictor of poor survival. Conversely, the tumor course may be indolent if the ST lesion is low-grade and non-progressive at the time of PF involvement. The possible mechanism(s) behind this tropism are also discussed.
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