Progressive visual disturbance in a 46 year old woman
We report a case of a 46 year old woman who presented with bilateral visual defects for 3 months. She had unilateral visual impairment since 9 months (left eye), followed by bilateral deficits, and no headaches. On examination, she had only bi-temporal hemianopsia. CT scan showed a hypodense suprasellar mass, with small foci of calcifications.MRI of the brain revealed a suprasellar mass with mainly isosignal on T1-WI, mild high signal on long TR sequences, enhancing non-homogeneously after gadolinium.
Surgical treatment was tried but resection of the tumor was not possible - the margins of the tumor were not defined from normal brain tissue. Biopsy was done and histopathology diagnosis was optic ganglioglioma. The patient is under clinical and MR follow-up since 2 years and remains stable.
Gangliogliomas are mixed glioneuronal tumours, relatively benign slow-growing. They are rare, accounting for approximately 0.4-1.3% of all brain tumours, occurring mostly in the paediatric population (7.6%). they most often involve temporal lobes, and occur less commonly in the frontal and parietal lobes. Gangliogliomas involving the hypothalamus and optic chiasm are extremely rare. All of cases reported are associated with visual impairment. Gangliogliomas are characterized on CT scans as hypodense lesions with calcification and a variable contrast enhancement pattern.
The MR findings are nonspecific. The lesions may be iso- to hypointense on T1-weighted images and hyperintense on T2-weighted images. Cystic components occur in about 60% of gangliogliomas; in other cases the lesions consist entirely of solid components. Cystic components can show higher signal intensity than does CSF on T2-weighted images, representing gelatinous material. However, 40% of cases appear as solid lesions only. Contrast enhancement are variable, and can be either a nodular rim or a solid enhancement pattern.
The histopathologic criteria for diagnosis of ganglioglioma include neoplastic astrocytes and atypical neurons. The ganglion cells must be distinguished from pre-existing non-neoplastic neurons, which might have been incorporated into an astrocytoma.
The normal optic chiasm does not contain ganglion cells. The neoplastic neurons in gangliogliomas in this region may have been derived from ectopic neural tissue.
Most CNS gangliogliomas are well circumscribed. Therefore, surgical excision is possible, resulting in a generally favourable prognosis. However, complete resection often cannot be accomplished in cases with chiasmatic involvement. The role of postoperative radiotherapy is controversial and usually reserved for those with disease progression or recurrence.
The differential diagnosis of suprasellar lesions is broad. The most common lesions in adults are meningiomas and suprasellar extension of pituitary adenomas, whereas in children, they are craniopharyngiomas and hypothalamic chiasmatic gliomas.
Metastases and granulomatous disease are less common. Few optic apparatus gangliogliomas have been reported in the literature. Although rare, gangliogliomas should be included in the differential diagnosis of lesions occurring in this area of the brain. We emphasize the importance of correct diagnosis by magnetic resonance imaging and subsequent resection for preserving and improving the visual function of patients with cavernous angiomas of the optic chiasm.
Differential Diagnosis List
Ganglioglioma of the optic chiasm
Ganglioglioma of the optic chiasm