Diagnostic Considerations
Gitelman syndrome
Gitelman syndrome is associated with hypokalemic metabolic acidosis and hypomagnesemia. Patients with Gitelman syndrome may have renal tubular acidosis and a history of pseudogout. Consequently, this diagnosis should be considered in patients with such findings.
Gitelman syndrome has been shown to be associated with a mutation in the gene solute carrier family 12, member 3 (SLC12A3). The cause may be related to the thiazide-sensitive sodium chloride cotransporter, which is found in a variant form in most patients with the syndrome.
Gitelman syndrome can mimic several other manifestations of calcium pyrophosphate deposition (CPPD) disease , including osteoarthritis, carpal tunnel syndrome, and tenosynovitis with calcifications along the tendon sheath itself. [23]
Septic arthritis
Septic arthritis can present as monoarticular arthritis and, therefore, can mimic acute pseudogout. Therefore, a Gram stain of the fluid should be performed. The results of the Gram stain will be negative unless a concomitant infection is present.
If septic arthritis is suggested clinically, even if crystals are seen on compensated polarized microscopy, it must be evaluated and, possibly, treated.
Other differentials
The differential diagnosis for pseudo-osteoarthritis includes hemochromatosis, hyperparathyroidism, hypothyroidism, and traumatic arthritis (as occurs in heavy-equipment machinery operators).
Basic calcium phosphate deposition disease and Lyme arthritis are also included in the differential diagnosis of CPPD.
See also The Approach to the Painful Joint.
Differential Diagnoses
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Calcium pyrophosphate deposition disease. Radiograph of the knee showing chondrocalcinosis involving the meniscal cartilage, as well as evidence of osteoarthritis.
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Calcium pyrophosphate deposition disease. Radiograph of the wrist and hand showing chondrocalcinosis of the articular disc of the wrist and atypical osteoarthritis involving the metacarpophalangeal joints in a patient with underlying hemochromatosis.
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Calcium pyrophosphate deposition disease. Appearance of calcium pyrophosphate dihydrate crystals obtained from the knee of a patient with pseudogout. The crystals are rhomboid-shaped with weakly positive birefringence, as seen by compensated polarized microscopy. The black arrow indicates the direction of the compensator.
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Calcium pyrophosphate deposition disease. High-powered view of calcium pyrophosphate dihydrate crystals with compensated polarized microscopy. The black arrow indicates the direction of the compensator. Crystals parallel to the compensator are blue, while those perpendicular to the compensator are yellow.
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Calcium pyrophosphate deposition disease. High-powered view of calcium pyrophosphate dihydrate crystals with compensated polarized microscopy. The crystals parallel to the compensator were blue, while those perpendicular to the compensator were yellow. However, the crystals have been rotated 90%, resulting in a color change in both of them. The direction of the compensator was not changed and is indicated by the black arrow.
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Calcium pyrophosphate deposition disease. Ultrasonography of the wrist demonstrates chondrocalcinosis.
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Intraoperative photographs demonstrate extensive precipitate deposition of the calcium pyrophosphate crystals in the articular cartilage, meniscus, and synovium of a knee. Left images depict femoral and tibial surfaces. Right images depict anterior cruciate ligament.
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Intraoperative photographs demonstrate extensive precipitate deposition of the calcium pyrophosphate crystals in the articular cartilage, meniscus, and synovium of a knee. Upper left image depicts anterior horn medial meniscus. Lower left image depicts undersurface of meniscus. Upper right image depicts medial femoral condyle. Lower right image depicts synovium.
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Calcium pyrophosphate deposition disease. Ultrasound scan of the triangular fibrocartilage complex (TFCC) of the wrist shows thin hyperechoic bands parallel to the surface of the hyaline cartilage. Other findings include a punctate pattern consisting of several hyperechoic spots and homogeneous hyperechoic nodular or oval deposits in the articular surface.
