Brown tumors are rarely the presenting feature of the hyperparathyroidism and are usually accompanied by a disturbance of the calcium-phosphate balance. We report the case of a 46-year-old patient with no medical history, presenting a solitary bone lytic lesion linked to primary hyperparathyroidism. Phosphate and calcium balance was within normal range initially thus resulting in delayed diagnosis. Bone lesion has subsequently been confirmed to be a brown tumor. In front of solitary lytic bone lesion and even if phosphate and calcium balance was normal; the dosage of parathyroid hormone must be performed.