Ossifying pituitary gonadotroph adenoma: A case report

Background. Bone formation in pituitary adenomas is a rare finding. Only two previous cases were published, occurring in a prolactin- producing and a growth hormone- producing pituitary adenoma respectively, both in pre-menopausal women. Clinical Material. This is the third report of an ossified pituitary adenoma and the first report of a pituitary gonadotroph adenoma with bone formation occurring in an elderly man. MRI imaging revealed an unusual eggshell cap-like calcified structure surrounding the tumor. Histologically, the adenoma contained irregularly anastomosing trabecules with well formed lacunae and osteoblasts along the margins. Conclusions. Insufficient tumor blood supply may trigger proliferation of connective tissue that subsequently undergoes osteoid metaplasia. Pituitary adenoma with osteoid metaplasia should be included in the differential diagnosis of calcifying tumors int eh sella region.