[A case of parathyroid adenoma localized in the middle mediastinum].

The discovery of a parathyroid adenoma in the middle mediastinum is exceptional and fewer than 10 cases have been reported. On the basis of a new case, the authors propose several pathogenic hypotheses: this adenoma develops and/or migrates from the fourth branchial pouch. Preoperative imaging is very useful for guiding the operation via sternotomy. The absence of any CT signs in the present case caused us to explore the retro-aortico-caval region. Sternotomies performed for the treatment of primary hyperparathyroidism are unsuccessful in one third of patients. In more than 30% of cases, the cause for this failure is related to the persistence of a cervical adenoma: when the pathological gland is actually located in the mediastinum, the possibility of middle mediastinal ectopia should be considered when investigation of the classical sites in the neck and mediastinum remains negative.