Brown tumor is a rare clinical entity. It’s an osteolyticand non neoplasic lesion due to hyperparathyroidism. This report describes the case of a 48 year old man who presentedwith a painless swelling in the mandible lasting for three months as chief complaint. The diagnosis of brown tumor was confirmed after performing the biopsy and doing the blood tests for calcium and parathyroid hormone levels which were severely high: 1962 pg/ml. those investigations led us to discover a parathyroid carcinoma. This work highlights the diagnosis challenges and pitfalls linked to this rare and poorly understood disease. It also emphasizes the interest of the early screening of such endocrinopathy.