CPPD crystal deposition disease or pseudogout Clyde A. Helms, M.D. * lames B. Vogler, Ill, M.D.t David A. Simms, M.D.+ Harry K. Genant, M.D. *
Chondrocelcinosis, arthropathy and joint pain are the hallmarks of the CPPD crystal deposition disease or pseudogout syndrome.
Introduction
Pseudogout is a syndrome caused by the deposition of calcium pyrophosphate dihydrate (CPPD) crystals in and about the joints of middle-aged or older adults. Three discrete manifestations of this deposition of CPPD crystals are recognized: (1) chondrocalcinosis; (2) typical arthropathy; and (3) the clinical presentation of pain. Any combination of these features may suffice to suggest the diagnosis of pseudo gout. It is the purpose of this presentation to illustrate the radiologic manifestations of the disease.
Chondrocalcinosis
Although CPPD crystals are not the only calcium salts that can produce chondrocalcinosis, they are present in the overwhelming majority of cases of radiographically demonstrable chondrocalcinosis. The classic pattern of calcification in the hyaline articular cartilage or the fibrocartilage of a joint almost invariably represents CPPD crystal deposition (Figures 1-5). It is important to realize that the patient with pseudogout mayor may not be symptomatic. Same clinicians prefer to attach the term "pseudogout" only to symptomatic patients, whereas others require only the presence of chondrocalcinosis. CPPD crystals can be found in any cartilage and even in the soft tissues where it may mimic calcific tendinitis (Figure 7). The knee, symphysis pubis, and triangular cartilage of the wrist are the areas most likely to be involved, and they should be examined closely in suspected cases.
* From the Department of Radiology, University of California, San Francisco, School of Medicine, San Francisco, CA 94122. t From the Department of Radiology, David Grant USAF Medical Center, Travis AFB, CA 94535. From the Department of Radiology, Wilford Hall USAF Medical Center, Lackland AFB, TX 78236. Address reprint requests to Dr. Helms.
*
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Chondrocalcinosis
Figure 1 Classic hyaline articular and fibrocartilage chondrocalcinosis in the knee.
Figures 2A & B Lateral projections of knees showing hyaline articular and fibrocartilage chondrocalcinosis. Note the chondrocalcinosis in the tibiofibular joint in Figure 2B (arrow).
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Pseudogoutsyndronle
Chondrocalcinosis
Figure 3 Typical chondrocalcinosis in the knee.
Figure 4 Triangular cartilage chondrocalcinosis (arrow). Note that the second metacarpophalangeal and radiocarpal joints are also affected.
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Chondrocalcinosis
Figures 5A & B Chondrocalcinosis of the symphysis pubis in two different cases. Note the chondrocalcinosis of the hip in Figure SA.
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Figures 6A & B Chondrocalcinosis in the spine typically occurs in the annulus (Figure 6A-arrows). Contrast this with chondrocalcinosis in the nucleus pulposis (Figure 6B). The latter is more common in the familial type of CPPD crystal deposition disease which is usually seen in Europe.
Figure 7 Tendinous CPPD crystal deposits in the heel.
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CPPD crystal deposition causes an arthropathy characterized by sclerosis, joint space narrowing, and osteophyte formation that is indistinguishable from degenerative joint disease except that it occurs in sites not usually involved in true degenerative joint disease. If "degenerative joint disease" is seen in the radiocarpal joint, the elbow, or in only the patellofemoral compartment of the knee joint, pseudogout should be considered, assuming that previous trauma can be excluded (Figures 8-11). Although CPPD crystals are always present in affected joints, they may or may not be demonstrable radiographically as chondrocalcinosis (Figure 12), and the affected joints mayor may not be symptomatic. The arthropathy of CPPD crystal deposition may also be manifest by the presence of large subchondral cysts or geodes (Figures 11, 12, and 14), and the lesion may cause massive articular disease and joints resembling neuropathic joints (Figures 13 and 14).
Arthropathy
Figures 8A & B Degenerative joint disease about the elbow is typical of the arthropathy of pseudogout. Note the "drooping" osteophytes which are said to be characteristic of this disorder.
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Arthropathy
Figures 9A & B Marked patellofemoral compartment disease (arrows); arthropathy is less marked in the medial and lateral compartments.
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Arthropathy
Figures lOA & B Another example of accelerated patellofemoral compartment disease (arrows).
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Arthropathy
Figure 11 Degenerative joint disease of the radiocarpal joint is one of the hallmarks of the arthropathy of pseudogout. Note the prominent geodes.
Figures 12A & B Subluxation, joint destruction and heterotopic new bone formation-the characteristics of a neuropathic joint-are all present in this knee which was laden with CPPD crystals. Chondrocalcinosis was present in other joints.
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Figures 13A & B Severe joint destruction and heterotopic new bone suggest a neuropathic joint; the findings are, in fact, the result of CPPD crystal deposition disease.
Figures 14A & B Joint destruction, subluxation and new bone formation in this wrist are typical of the findings in a neuropathic joint. This is the opposite wrist of the patient shown in Figure 11. Note the large geodes.
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Clinical Manifestations
The release of CPPD crystals from articular cartilage causes a reactive synovitis that is often confused clinically with gout-hence the name pseudogout. Its clinical presentations are so varied, however, that pseudogout has been called "the great mimicker." Primary hyperparathyroidism, gout, Wilson's disease, hemochromatosis, and hypophosphatasia are all disorders that are often associated with secondary deposition of CPPD crystals (Figures 15-17). They should be excluded whenever the diagnosis of pseudogout is considered. Although pseudogout has been shown in some instances to be familial (particularly in Europe) (Figure 6B), the vast majority of cases in the United States are sporadic.
Figure 15 This patient has the typical arthropathy of hemochromatosis; i.e., accelerated degenerative joint disease about the metacarpophalangeal joints with "drooping" osteophytes and chondrocalcinosis (arrows).
Figure 16 This patient has pseudogout and gout. Note the erosions withoverhanging margins (arrows) and the chondrocalcinosis (double arrows).
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Figures 17A, B & C This patient has hyperparathyroidism with healing brown tumors in the distal femur and left ilium. Note the chondrocalcinosis in the knee and symphysis pubis.
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Summary
CPPD crystal deposition disease or pseudogout is a syndrome that is manifest clinically as ..arthritis" and radiographically as chondrocalcinosis or as an arthropathy that resembles that of degenerative joint disease. When pseudogout is suspected, other metabolic disorders known to be associated with the secondary deposition of CPPD crystals should be excluded. The disorder is characterized by joint pain, chondrocalcinosis and arthropathy. Anyone of these features may be present in a given case, or they may coexist in any combination.
Additional Readings
1. Resnick D, et al. Clinical, radiographic, and pathologic abnormalities in calcium pyrophosphate dihydrate deposition disease (CPPD): Pseudogout. Radiology 1977; 122:115. 2. Genant HK. Roentgenographic aspects of calcium pyrophosphate dihydrate crystal deposition disease (pseudogout). Arthritis Rheum 1976; 19:307-328. 3. Jensen P, Putman C. Current concepts with respect to chondrocalcinosis and the pseudogout syndrome. Am J Roentgenol1975; 123:531-539. 4. McCarty D. Calcium pyrophosphate dihydrate crystal deposition disease (pseudogout syndrome)-clinical aspects. Clin Rheum Dis 1977; 3:61-89.
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