A rare case of silent pituitary macroadenoma with positive TSH and prolactin immunostaining

Silent thyroid stimulating hormone (TSH)-immunostaining pituitary adenomas are rare tumors, they can be either pure or immunoreactive to other pituitary hormones. We report a case of a silent macroadenoma with both TSH and prolactin immunostaining but with no clinical manifestations of hyperthyroidism or hyperprolactinemia. Pituitary magnetic resonance imaging revealed a macroadenoma. Transsphenoidal surgery was incomplete. The immunohistochemical staining showed that tumor cells were reactive to TSH (60%) and to prolactin (40%). Control pituitary imaging revealed a residual macroadenoma, and dopaminergic agonist treatment was administered. Mixed TSH and prolactin pituitary adenomas are rare and usually diagnosed incidentally or in the face of compression signs. Hormonal examinations for all patients who have a pituitary adenoma should be performed even in the absence of symptoms of hypersecretion. Pathological examination with immunostaining is key to diagnosis of clinically silent pituitary adenomas. Complementary therapies can be used when surgery is incomplete or contraindicated such as dopamine agonists and somatostatin analogs.