Imaging Characteristics of Calcium Pyrophosphate Dihydrate Crystal Deposition Disease

Abstract

An 88-yr-old woman without history of gout or other arthropathy presented to our physiatry clinic because of acute onset of painful swelling in her right wrist with local erythema, heat, and tenderness (Fig. 1A). Serum C-reactive protein level was 2.49 mg/dl, but leukocyte count, uric acid, and electrolytes levels were within normal limits. A plain film radiograph revealed chondrocalcinosis over her right radiocarpal joint and triangular fibrocartilage (Fig. 1B). Ultrasonography showed increased vascularity (Fig. 1C) and multiple hyperechoic deposits with punctate and amorphous patterns within the right triangular fibrocartilage (Fig. 1D). A small amount of clear and yellowish synovial fluid was aspirated under ultrasound guidance. Rhomboid-shaped, positively birefringent crystals were visualized under compensated polarized light microscopy of the aspirated synovial fluid (Fig. 1E). Therefore, calcium pyrophosphate dihydrate (CPPD) crystal deposition disease was confirmed. After being administered oral colchicine and nonsteroid anti-inflammatory drugs for 7 days, her right wrist pain gradually subsided. A physiatry clinic follow-up visit at 8 mos showed no recurrence of symptoms or signs.FIGURE 1: A photograph of the patient’s hands, demonstrating right wrist erythema and swelling (A). Chondrocalcinosis over right radiocarpal joint (arrow) and triangular fibrocartilage (arrowhead) in plain film (B). Ultrasonography demonstrating increased vascularity and multiple hyperechoic deposits with punctate and amorphous patterns within the right triangular fibrocartilage (C and D) (arrowheads; Tr, triquetrum; U, ulna). Positively birefringent CPPD crystals under compensated polarized light microscopy (E). CPPD, calcium pyrophosphate dihydrate.CPPD crystal deposition disease is the third most common inflammatory arthritis, characterized by acute or chronic inflammation caused by deposit of CPPD crystals in articular cartilage and periarticular soft tissues, mostly in knees and wrists.1,2 The character of rapid-onset arthritis is highly suggestive of crystal-induced arthropathy but is not specific for CPPD.1 Although the definitive diagnosis of CPPD crystal deposition disease is based on identification of positively birefringent CPPD crystals in the synovial fluid or biopsied tissue,1 several imaging techniques have proven to be helpful in delineating this clinically perplexing condition.1–4 In this case, the presence of radiographic chondrocalcinosis, coupled with advanced age, alerts the clinician to consider the possibility of CPPD crystal deposition disease.1,3 High-resolution ultrasonography provides further confirmation by identifying the sparkling reflectivity of CPPD crystal aggregates.2,4 Sonographic features of CPPD deposits depend on the amount and distribution, varying from homogeneously punctate pattern or sharply defined hyperechoic bands within the articular cartilage or floating in synovial fluid to rounded or amorphous-shaped hyperechoic areas in fibrocatilage.2,4The shape and location of CPPD crystal aggregates are also helpful in distinguishing from other crystal arthropathies,3 particularly gout, in which monosodium urate crystals tend to result in hyperechoic enhancement on the superficial margin of hyaline artilage.4 The imaging characteristics shown in this case are typical for CPPD crystal deposition disease and are of great value in establishing the final diagnosis. Advances in imaging techniques, especially high-resolution ultrasonography, may greatly improve the diagnosis of CPPD crystal deposition disease in physiatry practice.