Unilateral giant cell lesion of the jaw in Noonan syndrome.

Noonan syndrome (NS) is an etiologically heterogeneous disorder caused by mutations in the RAS-MAPK signaling pathway. Noonan-Like/Multiple Giant Cell Lesion (NL/MGCL) syndrome is initially described as the occurrence of multiple gnathic giant cell lesions in patients with phenotypic features of NS. Nowadays, NS/MGCL syndrome is considered a variant of the NS spectrum rather than a distinct entity. We report the case of a 14-year-old female patient carrying a SOS1 mutation with a unilateral giant cell lesion of the right mandible. Cross-sectional imaging such as CT and MRI are not specific for the diagnosis of oral giant cell lesions. Nonetheless, intralesional scattered foci of low SI on T2-WI, corresponding to hemosiderin deposits due to hemorrhage, can help the radiologist in narrowing down the differential diagnosis of gnathic lesions in patients with NS.