TRH and pituitary gland adenoma: Noteworthily, pituitary hyperplasia has no histopathological atypia or pathologic mitosis, and hormone replacement therapy can be effective.[10–13] However, pituitary adenoma is a benign neoplasm originating from anterior pituitary cells with necrosis and/or cystic changes.[7,14] We speculate that pituitary adenoma shares similar pathogenetic mechanisms with pituitary tumorous hyperplasia: long-term stimulation by TRH and loss of thyroxine feedback inhibition.