Abstract
Objective In general, glioblastomas multiforme (GBM) arise in the supratentorial region, but
in less than 4% of cases they also occur in the posterior fossa, particularly in the
cerebellum. Furthermore, a minority of malignant gliomas are multifocal. We report
on an unusual case with infratentorial multifocal lesions, suspicious for metastases,
which turned out to be a multifocal GBM of the posterior fossa.
Patient and Method A 69-year-old woman presented with recurring episodes of vertigo, headache, and progressive
weight loss. Three multifocal cerebellar and brainstem lesions highly suspicious for
metastases were identified by magnetic resonance imaging (MRI). Workup for malignancy
elsewhere in the body was negative.
Results The patient underwent craniotomy with successful resection of the tumor in the cerebellar
vermis with an excellent outcome and uneventful postsurgical course. Histopathology
of the tumor revealed features consistent with the diagnosis of GBM and ruled out
metastatic lesions. Workup for molecular genetics characterized this tumor as a primary
GBM. The patient initially responded to treatment with radiation therapy and temozolomide
but died after 10 months with a tumor relapse.
Conclusion We discuss the unusual aspects of multifocal primary GBMs in the posterior fossa.
Although rare, they should be considered in the differential diagnosis of cerebellar
tumors, which stresses the importance of a surgical treatment to establish a histological
diagnosis because there are no reliable radiographic criteria for distinguishing multifocal
infratentorial gliomas from multiple metastases and other tumor entities. The differentiation
between a primary and secondary cerebellar GBM did not lead to any change of the treatment
strategy in this case.
Keywords
glioblastoma multiforme - multifocal - posterior fossa - infratentorial
