Diagnosis and therapy for Cushing's disease with negative dynamic MRI finding: a single-centre experience.

OBJECTIVE: Most patients with Cushing's disease (CD) will have evidence of an adenoma on high-resolution magnetic resonance imaging (MRI). However, a significant minority of patients with CD and biochemical hypercortisolaemia have no visible adenoma on MRI. The purpose of this study was to evaluate the diagnostic value of preoperative biochemical assessment and accuracy of MRI findings on surgical outcome.
DESIGN: Retrospective data set analyses. PATIENTS AND MEASUREMENT: The clinical, endocrinological, histopathological and surgical outcomes of 24 consecutive CD patients with negative MRI findings were compared with those of 95 consecutive age- and sex-matched CD patients with pituitary adenomas on MRI.
RESULTS: The total remission rate was 86.6%. Among all patients, 87 had concordant positive endocrine tests and underwent neurosurgery, while bilateral inferior petrosal sinus sampling (BIPSS) was performed in 12 and 50 other patients with negative and positive MRI, respectively. A pituitary adenoma, confirmed by pathological examination, was found in 83.3% and 93.6% of patients with negative and positive MRI, respectively. The remission rate was not different between patients with negative and positive MRI (87.5 % and 86.3%, respectively; P > 0.05) or between patients who did not undergo BIPSS with negative MRI and patients with positive MRI (P > 0.05). The remission rate of patients who underwent BIPSS with negative MRI was not different from those not undergoing BIPSS (P > 0.05). The recurrence rate was higher, although not statistically different, in patients with negative MRI compared to positive ones.
CONCLUSIONS: Based on the findings outlined, MRI-negative CD may be a surgically remediable syndrome, with a pathophysiological basis that primarily involves a pituitary cause of the hypercortisolaemia.