Magnetic resonance imaging findings of pituitary hyperplasia due to primary hypothyroidism.

Objective: To explore the clinical and magnetic resonance imaging (MRI) findings of pituitary hyperplasia due to primary hypothyroidism.

Method: The clinical presentations, laboratory examinations, and MRI findings of 11 patients with pituitary hyperplasia secondary to primary hypothyroidism diagnosed at our hospitals from the beginning of 2008 to the end of 2011 were retrospectively reviewed.

Results: The clinical manifestations in 11 patients included growth arrest(7/8), mental retardation (6/8), cold intolerance and fatigue(6/11), slightly increased body weight (6/11), galactorrhea (3/11), paramenia (8/9), precocious puberty companying vaginal bleeding (2/2),and blurry vision (3/11). Laboratory investigations revealed grossly increased thyroid stimulating hormone, decreased thyroxine, and slightly elevated prolactin levels in all cases. Thyroid antibody was positive in six cases. On MRI, pituitary mass were detected a large intrasellar with/without suprasellar extension in all patients,showing the characteristic of symmetric enlargement. Spherical shape was viewed in 5 cases,with the height of (12.22 ± 3.12)mm. In the other 6 cases, the pituitary mass with the shape of calabash extended superiorly to suprasellar area, with a height of(18.95 ± 2.23)mm. The signal of pituitary mass was isointense to grey matter both on T1 weighted imaging and T2 weighted imaging. Bright short T1 signal in posterior lobe of pituitary was visible. Pituitary stalk was detected only in 4 cases from MRI without dislocation, while the width of pituitary stalk was within the normal limit.

Conclusions: Pituitary hyperplasia should be considered when homogenous enlargement of the pituitary gland is found on MRI. The integration of MRI findings, clinical manifestations, and laboratory findings is helpful for the proper identification of the primary endocrine disease and thus avoid misdiagnosis.