Pituitary enlargement mimicking pituitary tumor.

Primary hypothyroidism can result in reactive enlargement of the pituitary gland which is indistinguishable from primary pituitary lesions on computerized tomography (CT) scans. The presenting symptoms may be due to pituitary gland enlargement, as in two of the three cases reported here. Therefore, the diagnosis of pituitary hypertrophy or hyperplasia secondary to hypothyroidism must be based on the endocrinological work-up. Following treatment of primary hypothyroidism, the diminution in size of the pituitary gland can be demonstrated with CT.