Abstract Background Osteitis fibrosa cystica is a rare. benign and osteolytic lesion attributed to hyperparathyroidism. The high level of parathyroid hormone cause rapid bone loss. Case presentation The patient is a 50-year-old male complaining of severe and persistent pain in the right knee joint. https://www.jmannino.com/quick-offer-Viqua-F4-50-Plus-Monitored-UV-System-Powered-by-UVMax-15-gpm-230-Volt-on-sale/