[A rare case of HGH producing adenoma in direct contact with an IC medial type aneurysm].

A rare case of HGH producing pituitary adenoma which was in direct contact with right IC medial type aneurysm was reported. A 60-year-old woman was admitted to our clinic in February, 1981, for the acromegalic features, who was treated by 5 mg/day of CB-154 since 1976 under the diagnosis of HGH secreting adenoma. The diagnosis of bitemporal hemianopsia was made in 1977, but it was disappeared at the time of admission to our clinic. A coronal section of computed tomography demonstrated a high contrasted tumor shadow in the sella turcica without definite suprasellar extension. A right carotid angiography showed the right IC-medial type aneurysm between the right posterior communicating artery and ophthalmic artery. In March, 2-81, direct neck clipping of the aneurysm and subcapsular removal of the adenoma were performed by the right frontal approach. From the operative findings it was concluded that the aneurysm was partially embedded in the adenoma tissue. Post operative course was uneventful except for the fact that the basal HGH level could not be normalized without CB-154 therapy. Many cases of association of cerebral aneurysm with pituitary adenoma were reported in the literature. However, direct contact between the tumor and the aneurysm could not be detected. This case seems the first report of the direct association of cerebral aneurysm with pituitary adenoma. Etiology for the unique combination of adenoma and aneurysm was discussed. It has been well known that the prolonged high level of serum growth hormone in acromegaly produces arteriosclerotic and degenerative changes in the arterial wall. It was speculated that the formation of the aneurysm in our case particular was due to the combination effects of the following events. That is, the direct mechanical pressure of pituitary adenoma to the right IC arterial wall, the arteriosclerotic or degenerative change of the arterial wall due to the prolonged exposure to the high level of HGH, and finally traction effect of the adenoma to the arterial wall because of the reduction of the size of the adenoma due to CB-154 therapy, all above mentioned influences were considered to contribute to the aneurysm formation. Finally, the preoperative bilateral carotid angiography is not unnecessary to the operative planning of the pituitary adenoma, especially when the adenoma was HGH producing one.