Primary hyperparathyroidism is a disease caused by exaggerated secretion of the parathyroid gland hormone, produced by an adenoma in 80% of cases. Ectopic adenomas occur in a small proportion of cases. Herein, the authors report a 72-year-old woman with a delayed diagnosis of primary hyperparathyroidism, produced by an intrathoracic adenoma, with a longstanding course, presenting with severe osteoporosis, multiple fractures, bone deformities, and neurologic impairments. Persistent hypercalcemia, high levels of alkaline phosphatase, and parathyroid hormone were documented and a paratracheal mass was found on a helicoidal tomography of the thorax. After surgical removal, the histopathological examination confirmed an ectopic adenoma of the parathyroid gland and the patient achieved some improvement in her clinical picture.