We describe a case of retro-tracheal mass of the visceral compartment of the mediastinun in a 79-year-old woman revealed by signs of tracheal compression. Visualization of a vascular image coming from the cervical zone on reconstructed injected CT, and biological demonstration of a primary hyperparathyroidism led to the diagnosis of ectopic parathyroid adenoma, in spite of the cystic aspect of that tissular mass. Surgery by cervical approach was able to remove this mass without any problem. Pathological examination confirmed that it was a parathyroid adenoma with necrotic modifications. Follow up show a clinical and a biological improvement.