Snapshot A 60-year-old man presents to the emergency department for severe left knee pain. His symptom began approximately 8 hours prior to presentation. He denies trauma to the joint and this is the first time this occurred. Medical history is significant for hemochromatosis managed with weekly phlebotomy. On physical exam, the left knee is erythematous, warm, enlarged, and tender to palpation. Radiography of the affected joint demonstrates chondrocalcinosis. Joint aspiration demonstrates a leukocyte count of 2500/mm3 with a negative Gram stain. Polarized microscopy shows weakly positively birefringent rhomboid crystals. Introduction Clinical definition login to view 1 more bullet Epidemiology Risk factors login to view 2 more bullets Etiology CPP deposition in joints Pathogenesis login to view 3 more bullets Associated conditions login to view 6 more bullets Presentation Symptoms login to view 15 more bullets Imaging Radiography login to view 5 more bullets Studies Arthrocentesis login to view 6 more bullets Differential Gout login to view 3 more bullets Treatment Conservative login to view 3 more bullets Medical login to view 10 more bullets Complications Joint damage Prognosis Acute attacks typically resolve in 10 days Patients may experience functional limitation due to joint damage May resemble osteoarthritis or rheumatoid arthritis