Gangliocytomas of the sellar region--a review

Gangliocytomas are benign, slow growing neuronal tumors and are found for the most part in children and young adults. They are most often localized in either the spinal cord or the cerebral hemispheres. Gangliocytomas in the sellar region are extremely rare and only 43 such tumors (including 4 own cases) have ever been described in the literature. Although these tumors are genuine rarities without any epidemiological importance, they do provide some interesting information on tumorigenesis of pituitary adenomas: 65% of the sellar gangliocytomas are associated with a pituitary adenoma. 74% of patients with these tumors suffered hormonal oversecretion of at least one of the pituitary hormones (mostly growth hormone). With only one exception, the hypothalamic releasing hormone corresponding to the hormonal oversecretion syndrome could be demonstrated in the gangliocytoma immunohistochemically. Ultrastructural studies could demonstrate close cell to cell contacts between adenoma and gangliocytome cells. All these data support the hypothesis that chronic overstimulation by hypothalamic releasing hormones play a role in the development of hormone secreting pituitary adenomas. However, in contrast to sellar gangliocytemas, extrahypothalamic tumors secreting excessive hypothalamic hypophysiotropic hormones have never been associated with a pituitary adenoma. They have only been associated with pituitary cell hyperplasia. Therefore, the hypothesis can be made that hypothalamic releasing hormones only promote but do not initiate tumorigenesis of pituitary adenomas.