PRIMARY DIFFUSE CHIASMATIC GERMINOMAS - DIFFERENTIATION FROM OPTIC CHIASM GLIOMAS

Primary germ cell tumors confined to the optic nerves and chiasm witho ut suprasellar extension are uncommon. These tumors appear similar to chiasmatic gliomas on both computed tomography and magnetic resonance imaging, potentially resulting in treatment errors if the diagnosis is based on radiologic criteria alone. Unlike chiasmatic gliomas, supras ellar germinomas characteristically present with a clinical triad of e ndocrine abnormalities, diabetes insipidus, and visual complaints; We report the case of a 9-year-old boy who presented with a 5-month histo ry of fatigue, 16-pound weight gain, polydipsia, polyuria, visual comp laints, and intermittent headache. Imaging studies demonstrated findin gs consistent with a glioma of the chiasm with infiltration into the o ptic tracts. At surgery, the chiasm and optic tracts were diffusely en larged with no other suprasellar abnormalities. Biopsy specimens were characteristic of germ cell tumor. Based on this result, the patient r eceived a treatment regimen different from that used at our institutio n for chiasmatic gliomas. We feel it is imperative to biopsy chiasmati c lesions that radiologically appear to be gliomas if symptoms do not adhere to the classical clinical presentation.