Ectopic ACTH syndrome in a dog with a mesenteric neuroendocrine tumour: a case report.

Ectopic ACTH secretion is provoked by extra-pituitary tumours that secrete ACTH, constituting an infrequent type of Cushing Syndrome in the dog. Neuroendocrine tumours (NET) are characterised by the synthesis of peptides with hormone activity. A dog with clinical diagnosis of Cushing's syndrome and presenting an abdominal tumour located in the area of the left adrenal gland was sent to the hospital. Cortisol was not inhib - ited at four and eight hours after the application of low-dose dexamethasone and the cortisol/creatinine ratio was elevated (93 × 10 -6 , reference values < 10 × 10 -6 ). Plasma ACTH measurements were high (28.6 pmol/l, reference values 5.5-14.3 pmol/l). On computed tomography, the tumour was found in the meso-epigastrium, with both adrenal glands hyperplasic and no alteration of the pituitary image. The tumour was located between the two layers of the meso-colon and was removed using laparoscopy. After surgery, ACTH concentrations became normal and clinical signs remitted. The histopathological diagnosis was NET, with positive ACTH immunostaining.