ESPE Abstracts

Background: Noonan syndrome (NS) is a congenital polymalformative disorder caused by aberrant up-regulated signalling through RAS GTPase. Although NS is associated with hematologic malignancies, no predisposition for neuronal tumors was reported so far.

Objective and hypotheses: We describe two cases of young patients with NS and dysembryoplastic neuroepithelial tumor (DNET). This is the first case series reporting a rare type of intracranial tumor in NS.

Results: First case is a boy introduced to the Neuropediatric Department at 13 years of age because of recurrent paroxysmal paresthesia, lasting for about 15 s. He was diagnosed with NS at the age of 6 years, after workup for delayed growth, with genetic confirm of heterozygous mutation of PTPN11 gene exon 3. Clinical examination was unremarkable. The cranial MRI showed an ~3×3×2 cm lesion in the left parietal lobe, without sign of compression. The morphology corresponded to a DNET. The diagnosis was biopsy-proven afterward and anticonvulsive therapy was initiated. After repeated consideration of possible risks, GH therapy was started 1 year after the initial diagnosis and suspended after 6 months because of tumor growth.

Second case is a 13 years old asymptomatic boy who presented to Endocrinology Clinic with delayed growth. He received a diagnosis of NS because of typical phenotype and cardiac malformations (genetic diagnosis confirmed PTPN11 mutation). A MRI, performed after starting GH therapy, reported an oval lesion in the right parietal-occipital cortex, with greater diameter of 3 cm, consistent with DNET. GH therapy was cautiously stopped.

Conclusion: DNET is a rare intracranial tumor, diagnosed in young patients with seizures or more rarely in asymptomatic patients, characterized by good prognosis. Because of the possibility intracranial tumors, a brain MRI is mandatory in NS patients before starting GH therapy.