Primary hypothyroidism in a child mimicking a pituitary macroadenoma.

We report the case of an 11-year-old girl with primary autoimmune hypothyroidism causing secondary pituitary enlargement. She presented with headaches and a pituitary mass on MRI thought to be due to a pituitary macroadenoma. Resolution of the pituitary mass and symptoms occurred with thyroxine therapy. It is mandatory to rule out primary hypothyroidism as a cause of pituitary enlargement before surgery is considered.