Rosette forming glioneuronal tumor in association with Noonan syndrome: pathobiological implications

Noonan syndrome, a distinctive syndrome characterized by dysmorphism, cardiac abnormalities and developmental delay, has been associated with a number of malignancies, however, only a few cases of primary glial or glioneuronal neoplasms have been reported. We report here the case of an 18-year-old with Noonan syndrome who developed a rosette forming glioneuronal tumor of the posterior fossa. The tumor demonstrated strong pERK immunoreactivity, suggesting MAPK/ERK pathway activation. Molecular testing did not reveal BRAF rearrangements (fusion transcripts) by PCR or a BRAFV600E mutation by sequencing. We review the literature regarding the molecular pathogenesis of Noonan syndrome and primary brain tumors, and consider the intriguing link between their common molecular pathways.