Biochemical cure of acromegaly after transsphenoidal surgery despite residual tumor on magnetic resonance imaging

A 52-year-old acromegalic woman underwent transsphenoidal removal of a pituitary macroadenoma. The tumor was totally removed apart from the part invading the right cavernous sinus. Postoperative magnetic resonance (MR) imaging demonstrated small residual tumor, but her acromegaly was cured using current strict criteria. The histological diagnosis was somatotroph cell adenoma with fibrous bodies. This biochemical cure persisted with no change in the residual tumor on MR imaging for 9 years without further treatment. Biochemical cure may not reflect total removal of the tumor, particularly if the growth hormone secretory activity of the residual tumor is low. Careful evaluation of postoperative MR imaging is always necessary to interpret surgical outcome, even if biochemical cure in acromegaly has been achieved.