Growth hormone secreting adenoma with unusual extension: coexisting pituitary cyst and its clinical significance

A 58 year old man showed acromegalic features. The serum growth hormone (GH ) level was 7.3ng/ml and SMC (somatomedin-C) 637 U/ml. Triple stimulation t est showed abnormal response compatible with a GH secreting tumour. The con ventional enhanced MRI revealed a less enhanced hemisphere-shaped lesion at the right corner of the sella turcica. In addition, dynamic MRI demonstrat ed an elongated lesion extending to the left beyond the midline, The patien t underwent transsphenoidal surgery. Besides the soft and suckable tumour a t the right corner, we entered into a small cavity loosely filled with the tumour, which was subsequently also removed. The operative finding correspo nded to the lesion shown in dynamic MRI. Postoperative GH and SMC levels be came 2.3 ng/ml and 326 U/ml respectively. Incidental pituitary cystic lesions in autopsied cases have been reported t o be 6-33%. This case had a GH secreting adenoma with coexisting pituitary cyst. The coexisting pituitary cyst supposedly influenced the unusual shape and extension of the pituitary adenoma. Coexistence of such lesion should be kept in mind for microadenoma on neuroradiological evaluation and on int raoperative inspection surrounding the tumour. (C) 2000 Harcourt Publishers Ltd.