Pituitary adenomas and granular cell tumors - Incidence, cell type, and location of tumor in 100 pituitary glands at autopsy

Incidentally detected pituitary adenomas were investigated in 100 pituitary glands at autopsy to determine the number cell type, and location of tumor s, and the presence of coexisting granular cell tumors in the neurohypophys is. Pituitary glands were sagittally sectioned at 1.5-mm intervals in tote and embedded in I cassette to orient location of each tumor: Twenty-four pi tuitary glands harbored adenomas, most smaller than 3 mm and the largest 6 x 5 x 4 mm. Two pituitary glands contained double adenomas of immunocytoche mically different cell types. Of the 26 adenomas, 10 had lactotrophs, 2 had mixed lactotrophs-somatotrophs, I had mixed lactotrophs-luteinizing hormon e cells, and 12 were nonfunctioning. One adenoma with adenocorticotropic ho rmone cells was also detected. Thus 25 of 26 (96%) adenomas were either lac totrophic or nonfunctioning; this percentage is much higher than that of su rgically resected tumors. Twenty-two tumors were contiguous with or adjacen t to the capsule from which the adenomas originated. Nine granular cell tum ors were noted in the neurohypophysis; 3 coexisted with pituitary adenomas. Fourteen additional cases revealed small granular cell nests. Thus the inc idental finding of nonfunctioning pituitary adenomas is relatively common i n adults (24% of cases in this study), and the coexistence of pituitary ade nomas and granular cell tumors may suggest a possible histogenic connection between anterior and posterior pituitary tumorigenesis.