Knee brown tumor revealing a primary hyperparathyroidism: a case report.

Primary hyperparathyroidism is a common endocrine disorder, asymptomatic and diagnosed through a fortuitous hypercalcemia. Brown tumors are exceptional but severe hyperparathyroidism bone complications. We report in this paper an original observation of hyperparathyroidism due to a parathyroid adenoma presenting as a brown tumor. A 28 year-old girl admitted for a bone tumor of the knee, the blood test shows hypercalcemia with hyperparathyroidism, bone biopsy revealed giant cell lesions characteristic of brown tumors.