ABSTRACT
BACKGROUNDS: Pituitary hyperplasia can mimic pituitary adenoma. In MRI, enlarged pituitary gland is enhanced homogenously with upward convexity of the superior margin of the gland .The best definition of hyperplasia in the pituitary hyperplasia seems to be a multiplication of one or more cell types. But definition, etiology and clinical courses of this disease are not clear, METHOD: We reviewed clinical symptoms, MRI, and pathologic findindings in 6 patients with pituitary hyperplasia. RESULT: 1. Major clinical symptoms were headache (100%), visual field defect (84%), polyuria/polydipsia (64%), and irregular mensturation (32%). Other symptoms were amenorrhea (16%) and galactorrhea (16%). 2. Three of five cases showed abnormal responses to combined pituitary function test, 3. MRI findings were pituitary hyperplasia (4), macroadenoma (l), and microadenoma (1). 4. In two operated cases, there was no adenoma. One case showed hyperplasia of lactotroph cells, the other was hyperplasia of gonadotroph cells confirmed by the examination of immunocytochemistry. CONCLUSION: Pituitary hyperplasia should be considered in patients with enlarged pituitary gland without focal mass lesion.