Silent, but not Unseen: Multimicrocystic Aspect on T2-Weighted MRI in Silent Corticotroph Adenomas

Introduction : Silent corticotroph adenomas (SCAs) present as nonfunctional pituitary tumors in routine preoperative evaluation. The objective of this study was to evaluate the diagnostic accuracy of MRI T2-weighted sequences for detecting the corticotroph subtype preoperatively. The preoperative T2-weighted MRI sequences were retrospectively evaluated in patients with SCA and two control groups: clinically manifest corticotroph macroadenomas (CSMs) and case-matched, nonfunctional gonadotroph macroadenomas (NFGMs). All were selected from a registry of 1,096 patients in whom transsphenoidal surgery was performed in the same tertiary reference center. T2-weighted MRI sequences were independently classified by one senior endocrinologist and one senior radiologist who were blinded to the clinical and histological features. Patients : Overall 17 patients with SCA, 14 with CSM, and 60 with NFGM were included in the study. Measurements: Pituitary MRI including T2-weighted sequences. Two aspects were retained: multiple microcysts (MMs) and the absence of microcysts. Hormonal data included plasma prolactin, IGF-1, testosterone or estradiol, LH, FT4, TSH, morning plasma cortisol, and an ACTH-stimulation test, when available. Results : MMs were present in 76% (13/17) of SCAs, 21% (3/14) of CSMs, and 5% (3/60) of NFGMs. The presence of MMs in clinically nonfunctioning macroadenomas had a sensitivity of 76% and a specificity of 95% for predicting SCA. Conclusion : The presence of MMs in T2-weighted MRI is a good diagnostic tool.