Two Different Pituitary Adenomas in a Patient with Multiple Endocrine Neoplasia Type 1 Associated with Growth Hormone-Releasing Hormone-Producing Pancreatic Tumor : Clinical and Genetic Features

The clinical and genetic features of a 43-year-old male patient with multiple endocrine neoplasia type 1 were reported. He developed hyperparathyroidism, a GHRH-producing pancreatic tumor, and acromegaly between 1980 and 1983. Because his pituitary gland increased in size even after resecting the GHRH-producing pancreatic tumor, transsphenoidal hypophysectomy was performed six years later. The pituitary contained two histologically-different adenomas composed of somatotroph cells and null cells. Genetic analyses revealed loss of heterozygosity on chromosome 11 in common in the pituitary adenomas, the pancreatic endocrine tumors, and a parathyroid hyperplasia. On the other hand, mutations of ras, p53, Gsα, and Gi2α genes were not found in these tumors. The loss of the tumor suppressor gene on chromosome 11q12-13 was involved in the formation of two pituitary adenomas, two pancreatic endocrine functioning tumors, and a parathyroid hyperplasia in this patient, but the tumorigenic factors in the specific endocrine organs remain to be studied.