Clinical Features and Remission Rates in Cushing's Disease: A Comparison of MRI-Detectable and MRI-Undetectable...

We aimed to characterize the clinical features and remission rates of patients with Cushing's Disease (CD) without magnetic resonance imaging (MRI) detectable pituitary adenoma compared to CD patients with MRI-detectable pituitary adenoma.All patients with adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (CS) without MRI-detectable pituitary adenoma underwent high-dose dexamethasone suppression test, corticotropin-releasing hormone stimulation test, and/or bilateral inferior petrosal sinus sampling (BIPSS). The diagnosis of CD in patients without MRI-detectable adenoma was confirmed when the results of dynamic testing and sampling concordantly indicated ACTH-producing adenoma.These patients were included in MRI-undetectable group. Patients with ACTH-dependent CS had pituitary adenoma≥6 mm and those with pituitary adenoma<6 mm but BIPSS findings indicative of CD were included in MRI-detectable adenoma group. The study included 60 patients without MRI-detectable adenoma and 74 patients with MRI-detectable adenoma. At presentation, patients without MRI-detectable adenoma were older [47 years (30.25-58) vs. 40.5 years (29-49), p=0.036]. Hypertension (65% vs. 47.3%), diabetes mellitus (58.3% vs. 39.2%), and cardiovascular disease (13.3% vs. 2.7%) were more common in patients without MRI-detectable adenoma (p=0.040, p=0.027, p=0.020; respectively). The transsphenoidal surgery as initial treatment was higher in the patients with MRI-detectable adenoma group (97.3% vs. 80%, p=0.001). Third-month remission (60.4% vs. 63.8%, p=0.700) after surgery, and remission rates in the last visit (65.3% vs. 79.7%, p=0.077) were similar between the two groups. Inconclusion, the absence of an MRI-detectable adenoma underscores the necessity for comprehensive management.