Hypothalamic-Opticochiasmatic Glioma

hypothalamic-opticochiasmatic glioma coronal

There is diffuse enlargement and increased T2 signal change of the optic chiasm and optic nerves. There is diffuse abnormal T2-hyperintense signal change also involving the hypothalamus, basal ganglia, thalami, pons and midbrain. The appearances are suggestive of hypothalamic-optochiasmatic pilocytic astrocytoma/ glioma.

This entity is a subset of astrocytic tumors which occur in patients with neurofibromatosis type 1. These may involve the optic nerves, the optic chiasm, and the optic tracts. Most are juvenile pilocytic astrocytomas, but their imaging characteristics are not specific with regard to their histologic features. Varying degrees of cystic change and enhancement are demonstrated. These tumors may appear smooth, fusiform, eccentric, or lobulated.

Gliomas of the optic chiasm and hypothalamus account for 10%–15% of supratentorial tumors in children. Males and females are approximately equally affected. Between 20% and 50% of patients with hypothalamic gliomas have a positive family history of von Recklinghausen disease (NF-1). Gliomas of the optic chiasm and hypothalamus in children with NF-1 usually have a more indolent course. Tumors may grow more slowly and occasionally regress spontaneously. MR imaging is optimal for showing the relationship of the mass to the hypothalamus, optic chiasm, and infundibulum as well as the intraorbital and intracanalicular components of the mass. Gliomas of the optic chiasm and hypothalamus are almost always hypointense with T1-weighted sequences and hyperintense with T2-weighted and FLAIR sequences. Large tumors are typically heterogeneous with cystic and solid components, with the latter often enhancing after contrast administration.

Reference: Kollias SS, Barkovich AJ, Edwards MS. Magnetic resonance analysis of suprasellar tumors of childhood. Pediatr Neurosurg 1991–1992; 17: 284–303.

Credit: Dr Abhijit Datir