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://poolsproductscanadas.shop/product-category/hayward-hcp-4000-series-parts/