irkman et al., by reporting on their experience at National Hospital for Neurology and Neurosurgery of London K with thyrotropin (TSH)-expressing pituitary adenomas, have contributed an important and welcomed addition to the literature about pituitary tumors. Their series is one of the largest of TSH adenomas and is the first one reporting separately on those with clinically active and clinically silent forms. TSH adenomas are rare lesions of the pituitary. According to the literature, they occur in 1% 3% of large series of pituitary adenomas and are the least common of the secretory adenomas (9, 10).