[Recurrent brown tumors as initial manifestation of primary hyperparathyroidism. An unusual presentation].

Primary hyperparathyroidism is a rather frequent pathology characterised by hypersecretion of parathormone (PTH) which is caused by adenomas in 85% of all cases. At clinical onset, the most common symptoms are hypercalcemia-related (pain due to kidney stones, polyuria, gastrointestinal and neurological disorders) while rarer symptoms are due to brown tumors, expansive lesions often found in fibro-cystic osteitis. A case in which the patient showed recurrent mandibular brown tumors as initial clinical symptoms of primary hyperparathyroidism is described. This patient was examined for hypercalcemia, and a tumor mass at the left inferior mandibular branch was found. The patient had undergone surgical removal of a tumor in the left mandibular some years before, which was diagnosed as osteoclastoma. Primary hyperparathyroidism was diagnosed during recovery, and surgical removal of the parathyroid adenoma and mandibular tumor was performed. A histological diagnosis of large cell brown tumor was made. A microscopic observation of brown tumors which are made up of large multinuclear osteoclastic cells can often be confused with other large cell tumors during diagnosis. It is therefore necessary to exclude the presence of hyperparathyroidism with ionised calcium and, in cases of high values, intact PTH (iPTH), before performing a histological diagnosis of a large cell bone tumor. Throughout the course of primary hyperparathyroidism, brown tumors might appear in the absence of other specific symptoms and localize at the level of a single bone segment.