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Comment The current patient had elevated levels of 24-hour urine free cortisol and midnight saliva cortisol and unsuppressed levels of morning cortisol after taking dexamethasone. These findings are a clear indication of Cushing’s syndrome, which is defined as autonomous cortisol over-production.1 As his random morning ACTH levels were also elevated, his Cushing’s syndrome was ACTH-dependent.1 Although the vast majority of ACTH-dependent Cushing’s syndromes are caused by ACTH-secreting pituitary tumours, some are caused by ACTH-secreting tumours from other organs (e.g. ectopic Cushing’s syndrome), such as the lungs and pancreas.2 The normal pituitary gland of this patient revealed by an MRI scan suggested ectopic Cushing’s syndrome, which was confirmed by inferior petrosal sinus sampling.1,2 Locating an ectopic ACTH-secreting tumour can be challenging as it is often small and difficult to find by conventional imaging such as CT, MRI including diffusion weighted imaging, octreotide scan or fluorodeoxyglucose PET.3,468Ga-DOTATATE PET utilises a positron-emitting radioisotope-linked somatostatin analogue and has much higher spatial resolution and sensitivity than an octreotide scan in identifying neuroendocrine tumours, which comprise most ectopic ACTH-secreting tumours.2,5,6 As shown in the current case, 68Ga-DOTATATE PET is usually combined with contrast-enhanced CT and is the most sensitive imaging method in locating a covert ectopic ACTH-secreting tumour.3