The gout you suffer from may be "fake"!

*For medical professionals to read for reference only, you will suffer less! Clinically, when you see a patient with red, swollen and painful joints, what is the first disease that comes to your mind? In today's case, let's find the "real culprit" together! Diagnosis of the patient's history **, female, 45 years old, bilateral knee pain and discomfort for several months, no history of out-of-hospital visits
.

A small amount of fluid was seen in the bilateral knee joint cavity during ultrasonography
.

Fig.
1 Long-axis section of the suprapatellar regionFig.
2 The short-axis section of the suprapatellar region can also show the effusion in the suprapatellar capsuleFig.
3 Scanning the knee articular cartilage, we can find the hyperechoic deposits in the left knee articular cartilage with velvet-like distribution Figure 4 Spotted and sheet-like hyperechoic deposits in the articular cartilage were also scanned in the knee articular cartilage.
Figure 5 Hyperechoic deposits in the cartilage.
Answer Click the blank space below to get the correct answer: B Did you answer correctly? In fact, after careful observation of the crystal deposits, it will be found that the crystal deposits in this case are inside the articular cartilage, not on the surface of the articular cartilage, which is significantly different from the MSU crystals deposited on the surface of the cartilage
.

Obviously this is not gout, but another crystal deposition disease - pseudogout! Figure 6 Why is the pseudogout sonogram called "pseudogout"? In 1961, McCarty et al.
, in a study of patients with gout-like arthritis, found that non-urate crystals were present in synovial fluid
.

X-ray diffraction analysis confirmed that these crystals were calcium pyrophosphate dihydrate (CPPD)
.

The deposition of these crystals in the joints can cause an arthritic reaction similar to gout, so this type of disease is called "pseudo-gout"
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CPPD is a type of metabolic arthropathy characterized by the deposition of calcium salts in articular cartilage and surrounding tissues
.

The incidence of CPPD increases with age.
It usually occurs after the age of 50.
The peak incidence is between 60 and 80 years old.
The incidence of elderly people over 80 years old is about 20% to 49%.
The prevalence of knee joint CPPD in adults is as high as 13%.
%
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The disease is very similar to gout in its acute onset and is often confused and referred to as pseudogout
.

Pseudo-gout is not difficult to distinguish.
Remember these 4 clinical manifestations and 5 major differences.
The clinical manifestations of pseudo-gout are very similar to gout.
Because many people do not understand this pseudo-gout clinically, it is very easy to treat it as gout
.

So what are the symptoms of pseudogout, and how to distinguish between real and fake gout? (1) The symptoms of pseudogout first appear in the knee joint, and the frequency of occurrence is the knee, ankle, wrist, elbow, hip and shoulder joints, often involving multiple joints
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(2) In acute attacks, joint swelling and pain (gout-like symptoms) are often present
.

Can be induced by trauma, surgery or other diseases
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(3) Chronic cases are often accompanied by effusion in the knee joint cavity, and occasionally heberden's nodes (small indurations that appear next to the finger joints in the case of osteoarthritis of the phalanx)
.

(4) Sometimes with hyperuricemia, it is easy to be misdiagnosed as gout
.

Severe cases can result in rapid destruction of the articular surfaces, similar to charcot arthropathy (neuroarthropathy) or stiffness of the spine, similar to ankylosing spondylitis
.

Differences: Table 1 Differences between gout and pseudogout The clinical diagnosis should not be careless.
The 6 major ultrasound manifestations should be kept in mind.
The gold standard for the diagnosis of pseudogout is the verification of calcium pyrophosphate crystals by Fourier transform red spectroscopy (FTIR), but because of its expensive clinical Application is limited
.

The most widely used is the Ryan-McCaty criteria, which include the presence of calcium pyrophosphate crystals on synovial fluid analysis and typical radiographic cartilage calcifications
.

Figure 7 Multifocal, clump-like purplish-blue calcified crystal deposits The American Rheumatoid Arthritis Clinical Study Group defined the ultrasound features of CPPD in fibrocartilage, articular cartilage, tendon, and synovial fluid
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The ultrasound manifestations of CPPD are summarized as follows: (1) articular cartilage, its calcification is a thin band-like hyperechoic parallel to the surface of the articular cartilage, and is 1-2 mm away from the bony articular surface, usually without posterior acoustic shadows, with a diameter of >10 mm can be accompanied by posterior acoustic shadows; the characteristic manifestation is that the crystal layer appears in the middle of the articular cartilage, and moves with the movement of the articular cartilage during dynamic scanning; when the crystal deposition is diffusely distributed, it forms a "double wheel", similar to the lower (2) Fibrocartilage, whose calcifications appear as punctate echoes or hyperechoic circular or irregular areas, and their location in the fibrocartilage can be determined by dynamic scanning; (3) Sliding Liquid, crystal deposition usually manifests as homogeneous point-like hyperechoic, by reducing the gain level, the reflectivity of the crystal can be increased; (4) tendon, its calcification is usually linear along the course of the tendon, and there may be rear shadows (5) Soft tissue, its calcification is the most rare, manifested as hyperechoic nodules or oval deposits in the soft tissue around the joint; if the calcified soft tissue resembles a tumor-like shape, it is very similar to tophi, and can also be misdiagnosed as a tumor; ( 6) Bone, whose calcification is manifested as not only cortical integrity, but less joint destruction
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What should I do if I have fake gout? Unlike gout, there is currently no specific drug for dissolving CPDD crystals.
Therefore, the treatment of pseudogout is also individualized.
Asymptomatic patients do not need special treatment
.

Drug treatment is mainly to reduce inflammation and relieve symptoms
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In the acute attack stage, oral non-steroidal anti-inflammatory drugs can be administered, and those with poor efficacy can be injected with glucocorticoids after aspiration of joint effusion under the guidance of ultrasound
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Aggressive surgical treatment of weight-bearing hip and knee joints can be performed
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Direct irrigation under arthroscopy can remove the hyperplastic synovium with crystals in the joint, delay or block the disease process, and the effect is better
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Although the incidence of pseudogout is not as high as that of gout, the etiology and treatment methods of the two are quite different
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If you or your relatives and friends have symptoms similar to gout, and the uric acid is within the normal range after repeated re-examination, it is recommended to check whether there is a possibility of pseudogout
.

References: [1] Wei Minjie, Ran Haitao, Zhang Maohui.
Application progress of musculoskeletal ultrasound in calcium pyrophosphate deposition disease [J].
Journal of Clinical Ultrasound Medicine, 2021, 23(05): 379-381.
Source of this articleHua Bin Ultrasound world information provided by Li Qingquan Editor in charge of Jie Xiaomi Cao Qian Copyright Statement