Calcium pyrophosphate deposition (CPPD) disease is an arthropathy caused by 
calcium pyrophosphate dihydrate (CPP) crystal deposits in articular tissues, 
most commonly fibrocartilage and hyaline cartilage. According to EULAR, four 
different clinical presentations can be observed: 1) asymptomatic CPPD; 2) 
osteoarthritis (OA) with CPPD; 3) acute CPP crystal arthritis; 4) chronic CPP 
inflammatory crystal arthritis. Acute CPP crystal arthritis is characterized by 
sudden onset of pain, swelling and tenderness with overlying erythema, usually 
in a large joint, most often the knee, wrist, shoulder, and hip. Occasionally, 
ligaments, tendons, bursae, bone and the spine can be involved. CPPD of the 
atlanto-occipital joint (crowned dens syndrome) can cause periodic acute 
cervico-occipital pain with fever, neck stiffness and laboratory inflammatory 
syndrome. Chronic inflammatory arthritis is characterized by joint swelling, 
morning stiffness, pain, and high ESR and CRP. The relationship between OA and 
CPPD is still unclear. The main problem is whether such crystals are directly 
involved in the pathogenesis of OA or if they are the result of joint 
degeneration. Diagnosis is based on evaluation of history and clinical features, 
conventional radiology, and synovial fluid examination. Non-polarized light 
microscopy should be used initially to screen for CPPD crystals based upon their 
characteristic morphology, and compensated polarized light microscopy, showing 
the crystals to be weakly positive birefringent, is recommended for definitive 
identification, although this last pattern only occurs in about 20% of samples. 
The main goals of CPPD therapy are control of the acute or chronic inflammatory 
reaction and prevention of further episodes.