Accuracy of microcystic aspect on T2-weighted MRI for the diagnosis of silent corticotroph adenomas.

Introduction: A single study suggested that silent corticotropinomas (SCAs) have a different imaging phenotype, with microcystic aspect on T2-weighted sequence of magnetic resonance imaging (T2-MRI). This study only analysed manifest and silent corticotropinomas and nonfunctioning gonadotroph adenomas. Therefore, the prevalence of microcystic patterns of other tumours is not known.

Aim: To analyse frequency of microcystic patterns on T2-MRI in all subtypes of pituitary adenomas and determine accuracy of this radiological finding for diagnosing SCA.

Methods: Consecutive pituitary adenoma patients who underwent surgery between 2013 and 2016 at a single centre were included. T2-MRIs were evaluated by a radiologist and an endocrinologist blinded to histological diagnosis.

Results: A total of 143 patients (52% female) with median age of 49 years (14-80) were included. Clinically, there were 90 nonfunctioning pituitary adenomas (NFPAs), 32 somatotropinomas, 13 corticotropinomas, five prolactinomas and three TSH-secreting adenomas. Of the patients with NFPA, 12 (13%) were SCAs, 73 (79%) were gonadotropinomas and five (6%) were positive for prolactin (three) or TSH (two). A microcystic pattern was observed in 16 tumours (11%): one somatotropinoma, one corticotropinoma, seven SCAs and seven gonadotropinomas, and in no prolactinomas or TSH-secreting adenomas. It was more common in SCAs than in other tumours (58.3% vs 6.9%, respectively, P < .001) and had a sensitivity of 58%, a specificity of 93% and an accuracy of 90% to define an SCA.

Conclusion: Microcystic aspect on T2-MRI is able to define SCA with a good accuracy and can be a useful tool, considering the more aggressive behaviour of these tumours.