AbstractObjectiveDiagnostic workup of Cushing disease (CD) involves imaging evaluation of the pituitary gland, but in many patients no tumour is visualised. The aim of this study is to describe the association of magnetic resonance imaging (MRI) findings with the postoperative course of paediatric and adolescent patients with CD.PatientsPatients with a diagnosis of CD at less than 21 years of age with MRI evaluation of the pituitary before first transsphenoidal surgery were included.MeasurementsClinical, imaging and biochemical data were analysed.ResultsOne hundred and eighty‐six patients with paediatric or adolescent‐onset CD were included in the study. Of all patients, 127 (68.3%) had MRI findings consistent with pituitary adenoma, while the remaining had negative or inconclusive MRI. Patients with negative MRI were younger in age and had lower morning cortisol and adrenocorticotropin levels. Of 181 patients with data on postoperative course, patients with negative MRI had higher odds of not achieving remission after the first surgery (odds ratio = 2.6, 95% confidence intervals [CIs] = 1.1–6.0) compared to those with positive MRI. In patients with remission after first transsphenoidal surgery, long‐term recurrence risk was not associated with the detection of a pituitary adenoma in the preoperative MRI (hazard risk = 2.1, 95% CI = 0.7–5.8).ConclusionsUp to one‐third of paediatric and adolescent patients with CD do not have a pituitary tumour visualised in MRI. A negative MRI is associated with higher odds of nonremission after surgery; however, if remission is achieved, long‐term risk for recurrence is not associated with the preoperative MRI findings.