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 lo calized in either the spinal cord or the cerebral hemispheres. Ganglio cytomas in the sellar region are extremely rare and only 43 such tumor s (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 tumorigen esis of pituitary adenomas: 65% of the sellar gangliocytomas are assoc iated with a pituitary adenoma. 74% of patients with these tumors suff ered hormonal oversecretion of at least one of the pituitary hormones (mostly growth hormone). With only one exception, the hypothalamic rel easing hormone corresponding to the hormonal oversecretion syndrome co uld be demonstrated in the gangliocytoma immunohistochemically. Ultras tructural studies could demonstrate close cell to cell contacts betwee n adenoma and gangliocytome cells. All these data support the hypothes is that chronic overstimulation by hypothalamic releasing hormones pla y a role in the development of hormone secreting pituitary adenomas. H owever, in contrast to sellar gangliocytemas, extrahypothalamic tumors secreting excessive hypothalamic hypophysiotropic hormones have never been associated with a pituitary adenoma. They have only been associa ted with pituitary cell hyperplasia. Therefore, the hypothesis can be made that hypothalamic releasing hormones only promote but do not init iate tumorigenesis of pituitary adenomas.