Aims: Thyrotropin-secreting adenomas (TSH-As) are rare and, according to the World Health Organization criteria (WHO 2004), a significative part of them present features of atypical adenomas at the time of diagnosis. The present study focuses on the frequency of “atypical adenomas” and the significance of this definition as regards the follow-up. Furthermore, their possible association with Hashimoto thyroiditis, leading to a delay in diagnosis, is presented.
Methods: Cases relative to patients who underwent transsphenoidal surgery between 1992 and 2006 were retrieved. Follow-up ranged from 6 to 180 months.
Results: Ten cases of TSH –As out of 908 pituitary adenomas were selected. Before surgery, eight patients had hyperthyroidism, one was euthyroid and another one showed hypothyroidism associated with Hashimoto's thyroiditis. All cases were macroadenomas, six of them invasive. Three cases met the criteria for classification as atypical. In none of the cases, including the three “atypical adenomas”, were clinical or radiological signs of recurrence observed.
Conclusions: The three cases with features of atypical adenoma didn’t recur nor metastatize, suggesting that, at least in the present series, a strict relationship between the morphological criteria for diagnosing atypical adenomas and the biological behavior may be sometimes lacking. Furthermore, the casual association of TSH –As with Hashimoto thyroiditis may led to an adjunctive delay in diagnosis, because of low thyroid hormone levels.