ACTH-dependent Cushing’s syndrome (CS) can be caused by an ACTH-secreting pituitary adenoma (Cushing’s disease, CD) or by ectopic production of ACTH (ectopic ACTH syndrome, EAS) by a vast array of benign or malignant tumours that can vary from small carcinoids (in various locations), to medullary thyroid cancer, small cell lung cancer, pheochromocytomas, or rarer tumours (1). Although CD is more frequent than EAS, and as a group patients with EAS tend to have more severe hypercortisolism, higher plasma ACTH plasma level, and higher prevalence of hypokalemia, no single feature is able to differentiate between the two conditions (2). Furthermore, the hormonal dynamic tests that are often used in the attempt of differentiating the two diseases lack accuracy. Even the technical radiological advancements that are available in modern medicine may be sometime misleading, resulting in misdiagnosis (3). Finally, the literature may occasionally be inaccurate, as in several series patients may be classified as having EAS from an unknown source when they actually have CD that escaped the diagnosis despite modern pituitary MRI imaging and sophisticated interventional radiology tests (4). As in many diseases, the prevalence, clinical presentation, and severity of disease can vary in different geographical areas and different medical institutions. This may be due to genetic or environmental factors, which include exposure to noxious factors and availability and access to health care, and patterns of referral to specialists or tertiary care centers. Therefore, it would be expected that in countries with easy access to health care (for example where a public health care system is accessible and free) one would observe less advanced disease. In addition, patterns of referral to tertiary care centers vary in different countries, potentially affecting the mixture of patient series from different hospitals. For this reason, knowing the pattern of presentation of a disease in a particular practice environment may help determining the likelihood of a diagnosis.