2019; ACTH; Adult; Alopecia; Amenorrhoea; Belgium; Bicarbonate; C-reactive protein; CD-56; CRH stimulation; CT scan; Chloride; Chromogranin A; Cortisol (9am); Cortisol (salivary); Cortisol day curve; Cortisol, free (24-hour urine); Dexamethasone suppression (low dose); Ecchymoses; Ectopic ACTH syndrome; Ectopic Cushing's syndrome; Endonasal endoscopic surgery; Esthesioneuroblastoma*; Face - change in appearance; Facies - moon; Female; Haematoma; Headache; Hirsutism; Histopathology; Hydrocortisone; Hypercortisolaemia; Hypernatraemia; Hyperpigmentation; Hypertension; Hypokalaemia; INSM1*; Immunohistochemistry; Immunostaining; Inferior petrosal sinus sampling; MRI; Metabolic alkalosis; Muscle atrophy; Myasthaenia; Obesity; October; Olfactory neuroblastoma*; Oncology; Otolaryngology; PET scan; Pituitary; Potassium; Radiotherapy; Resection of tumour; Sodium; Synaptophysin; Unique/unexpected symptoms or presentations of a disease; Urinalysis; Urine 24-hour volume; White