From the Guidelines
Pseudogout should be diagnosed based on clinical presentation and confirmed by joint aspiration with synovial fluid analysis showing characteristic calcium pyrophosphate crystals, as there is no specific treatment to eliminate these crystals 1. Pseudogout presents as acute, painful joint inflammation caused by calcium pyrophosphate crystal deposition. Patients typically experience sudden onset of severe joint pain, swelling, warmth, and limited range of motion, most commonly affecting the knee, wrist, ankle, or shoulder. Some key features of pseudogout include:
- Sudden onset of severe joint pain
- Swelling, warmth, and limited range of motion
- Most commonly affects the knee, wrist, ankle, or shoulder
- More frequent involvement of larger joints compared to gout
- More common in older adults, with risk increasing after age 60 Diagnosis requires:
- Joint aspiration with synovial fluid analysis showing weakly positive birefringent rhomboid-shaped crystals under polarized light microscopy
- Supporting diagnostic findings include chondrocalcinosis (calcification of cartilage) on X-rays and elevated inflammatory markers like ESR and CRP
- Laboratory tests may help rule out other conditions, but normal serum calcium, phosphate, and uric acid levels are typical in pseudogout Risk factors for pseudogout include:
- Advanced age
- Osteoarthritis
- Previous joint trauma
- Metabolic disorders like hyperparathyroidism, hemochromatosis, and hypomagnesemia Pseudogout can be differentiated from gout by crystal type, affected joints, and the absence of elevated uric acid levels, though they may occasionally coexist in the same patient, as noted in the management of CPP-associated arthritis 1.
From the Research
Pseudogout Presentation
- Pseudogout, also known as calcium pyrophosphate dihydrate deposition disease (CPPD), is an arthropathy caused by calcium pyrophosphate dihydrate (CPP) crystal deposits in articular tissues 2, 3.
- The disease can manifest in different clinical forms, including asymptomatic, acute, and chronic 2, 3.
- Acute CPP crystal arthritis is characterized by sudden onset of pain, swelling, and tenderness with overlying erythema, usually in a large joint, such as the knee, wrist, shoulder, or hip 2.
- Chronic inflammatory arthritis is characterized by joint swelling, morning stiffness, pain, and high ESR and CRP 2.
Diagnosis of Pseudogout
- Diagnosis is based on evaluation of history and clinical features, conventional radiology, and synovial fluid examination 2, 3.
- Non-polarized light microscopy should be used initially to screen for CPPD crystals based on their characteristic morphology 2.
- Compensated polarized light microscopy, showing the crystals to be weakly positive birefringent, is recommended for definitive identification, although this pattern only occurs in about 20% of samples 2.
- X-ray or ultrasound examination can also be used to aid in diagnosis, but definitive confirmation requires demonstration of calcium pyrophosphate dihydrate crystals in the synovial fluid 3.
Clinical Forms of Pseudogout
- Asymptomatic CPPD is the most common form of the disease 3.
- Acute CPP crystal arthritis is characterized by sudden onset of symptoms, similar to gout 2, 4.
- Chronic CPP inflammatory crystal arthritis is characterized by joint swelling, morning stiffness, pain, and high ESR and CRP 2.
- CPPD of the atlanto-occipital joint (crowned dens syndrome) can cause periodic acute cervico-occipital pain with fever, neck stiffness, and laboratory inflammatory syndrome 2.