A sparsely granulated, nonsecreting adenoma of the pars intermedia associated with galactorrhea in a male rhesus monkey (Macaca mulatta).

A pituitary mass was found at necropsy of a male Macaca mulatta. Hematoxylin and eosin-stained sections were consistent with a chromophobe adenoma. Ultrastructural examination revealed the tumor to be comprised predominantly of sparsely granulated cells. The tumor cells were negative for prolactin, somatotropin, adrenocorticotropin, luteinizing hormone, and thyrotropin by the peroxidase anti-peroxidase method. Other major lesions were gynecomastia and galactorrhea, testicular atrophy, ankylosing spondylitis, and amyloid deposition in the liver, spleen, adrenal, and intestinal tract.