Rheumatoid arthritis (RA) is the most common form of inflammatory arthritis and affects over 2 million Americans. In many cases, diagnosis is not easy. There are more than 100 kinds of arthritis. Most of them involve inflammation. When a patient goes to a rheumatologist to take a diagnosis, there is a process of exclusion to reach an appropriate diagnosis. This exclusion process is called "differential diagnosis".
Because many forms of arthritis, especially inflammatory forms of arthritis are similar, differential diagnosis may be a difficult approach. It is usually convenient to divide the differential diagnosis of rheumatoid arthritis into two groups. The first group is a non-infectious disease and the second group is a disease associated with infection.
Since the discussion is quite long, I chose to split the article into two parts.
The following is a partial list of inflammatory pathologies that can be seen in evaluating patients with arthritic inflammatory symptoms and not associated with infection.
RA is an autoimmune chronic inflammatory disease mainly including peripheral joints (hand, wrist, elbow, shoulder, hip, knee, ankle and leg). It can also affect non-articular structures such as the lung, the eyes, the skin, and the cardiovascular system.
RA develops slowly with nonspecific symptoms such as fatigue, malaise (loss of appetite), loss of appetite, low fever, weight loss, vagal ganglion pain, and explosive with inflammation involving multiple joints It may decline. Symptoms of a joint usually involve both sides of the body equally, and occur symmetrically to the left and right. Erosion - damage to joints - can be seen with X-rays. About 80% of patients have elevated levels of rheumatoid factor (RF) or anti-cyclic citrullinated antibody (anti-CCP) in the blood. There appears to be a correlation between the presence of anti-CCP antibody and erosion.
Juvenile rheumatoid arthritis (JRA) occurs in children younger than 16 years of age. There are three forms of JRA including small joints (1-4 joints), articulated joints (4 joints or more), and systemic onset or Still's disease. The latter condition is related to systemic symptoms including fever and rash in addition to joint disease.
Articulated JRA has characteristics similar to adult RA. It causes about 30% of JRA cases. Most children suffering from articulated JRA are RF negative and their prognosis is usually good.
Approximately 20% of patients with articulated JRA are elevated in RF, and these patients are at risk of chronic progressive joint injury.
The involvement of the eye in the form of inflammation called uveitis is a common finding in patients with positive anti-nuclear antibody (ANA), a blood test used for screening of small joint JRA, especially autoimmune diseases. Because uveitis does not cause symptoms, careful screening should be done in these patients.
SLE is an inflammatory chronic autoimmune disease including skin, joints, kidney, central nervous system, and vascular wall. The patient may present one or more of the following: a butterfly-shaped rash on the face affecting the cheek; a rash on the other part of the body; a susceptibility to sunlight; halitosis. Fluid around the lungs, heart, or other organs; renal abnormalities; low white blood cell count, low red blood cell count, or low platelet count; nerve or brain inflammation; positive results of ANA blood test; double stranded DNA Or a positive result of blood test of antibodies against other antibodies.
Patients with lupus may have significant inflammatory arthritis. As a result, lupus may be difficult to distinguish from RA, especially if there are no other features of the lupus. Advantageous clues to diagnosis of RA for lupus in patients with arthritis affecting articulation include lack of lupus characteristics, erosion (joint damage) seen in x-rays, elevation of RF and anti-CCP antibodies.
Polymyositis (PM) and dermatomyositis (DM) are the type of inflammatory myopathy. These conditions are typically associated with weakness of large muscles (involving both sides). In the case of DM, a rash exists. Diagnosis consists of finding the following: Increase in muscle enzyme level in blood [the two enzymes that are measured are creatine kinase (CPK) and aldolase], Signs and symptoms, electromyogram (EMG) - change in electrical tests, and positive muscle biopsy.
Furthermore, in many cases, abnormal antibodies specific for inflammatory muscle disease may rise.
In both PM and DM, inflammatory arthritis is present and may appear like RA. Both inflammatory myopathy and RA can affect the lungs. In RA, muscle function is usually normal. Also, in PM and DM, erosive joint disease is accidental. RF and anti-CCP antibodies are typically elevated in RA but not in PM or DM.
SA is psoriatic arthritis, reactive arthritis, ankylosing spondylitis, and intestinal diseased arthritis, which cause systemic inflammation and which preferentially attack parts of the spine and other joints where tendons attach to the bone It is a kind of. They may also cause pain and stiffness in the neck, upper and lower back muscles, tendonitis, bursitis, heel pain, fatigue. They are called "seronegative" type of arthritis. The term "seronegative" means that the test for rheumatoid factor is negative. For symptoms of adult SA,
o Back and / or joint pain;
o Morning stiffness.
o Tenderness near the bones.
o Inflammation of the skin.
o Inflammation of the joints on both sides of the body.
o Skin or mouth ulcer;
Rash on the bottom of the foot; and
o Eye infection.
Of course, there may be arthritis similar to that seen in RA. A careful history and physical examination can distinguish between these symptoms, especially when there is a clear disease of infection (psoriasis, inflammatory bowel disease, etc.). In addition, RA has little effect on the DIP joint, the last line of the finger joint. Diagnosis of SA is possible when these joints are involved in inflammatory arthritis. (Note: conditions known as inflammatory erosive tuberous osteoarthritis may also affect DIP joints). Rarely, in the case of psoriatic arthritis, there may be elevated RF and anti-CCP antibodies, but RF and anti-CCP antibodies are negative in SA.
Gout is caused by the deposition of monosodium urate (uric acid) crystals into the joints. Gouty arthritis is acute at sunset, is very painful and shows signs of significant inflammation in the test (red, warm, swollen joints). Gout affects almost all joints of the body, but it usually affects cooler parts such as toes, feet, ankles, knees, hands. Diagnosis is done by extracting fluid from inflamed joints and analyzing the fluid. Although it is diagnostic to show monosodium urate crystals in joint solution, elevated serum levels of uric acid may also be useful.
In most cases, gout is an acute unilateral disorder distinguishable from RA. However, in some cases, chronic erosive joint infections involving multiple joints may develop. And if toffi (deposits of uric acid) are present, it can be difficult to distinguish from erosive RA. However, crystal analysis of joints or lenses and blood tests should help distinguish RA from gout.
Calcium pyrophosphate deposition (CPPD), also known as pseudogout, is a disease caused by the deposition of calcium pyrophosphate dihydrate crystals in joints. The presence of these crystals in the joint causes serious inflammation. To establish a diagnosis,
o Detailed medical history;
o Withdraw fluid from the joint to confirm the crystal.
o Combined use of X-ray showing crystal precipitation in cartilage (cartilage calcification). And
o Blood test to exclude other diseases (such as RA and osteoarthritis).
In most cases, CPPD arthritis shows single joint inflammation. In some cases, the CPPD disease may exhibit chronic symmetric polyarthrosis arthritis similar to RA. RA and CPPD diseases can be asserted by joint exhalation, usually showing calcium pyrophosphate crystals, and blood tests, including RF and anti-CCP antibodies which are usually negative in CCPD arthritis. A complicated feature is that RA and CPPD can coexist.
Sarcoidosis is an inflammatory joint disease. The majority of patients with this disease have lung disease and eye and skin disease is the next most frequent sign of disease. Diagnosis of sarcoidosis can be done only with clinical and X-ray presentation, but for diagnosis it may be necessary to use tissue biopsy by demonstration of "non-casing granulomas".
Arthritis is present in 15% of sarcoidosis patients and is rarely a sign of disease only. In acute sarcoid arthritis, joint diseases usually develop rapidly. Knee, wrist, and hands can be involved, but it is symmetrical including the ankle. In most cases of acute illness, pulmonary and skin diseases also exist. Chronic sarcoid arthritis can be difficult to distinguish from RA. To distinguish RA from sarcoidosis, RA-specific blood tests such as RF and anti-CCP antibodies may be useful, but biopsy of joint tissues may be necessary for diagnosis.
Rheumatoid arthritis (PMR) is a disease that causes inflammation of the tendon, muscle, ligament and tissue around the joint. It is accompanied by major muscle pain, pain, morning stiffness, fatigue, possibly fever. Inflammation of large vessels may lead to blindness and aneurysms, but it may be related to temporal arteritis (TA), also called severe condition, giant cell arteritis. In addition, due to insufficient blood flow (claudication of limbs) symptomatic syndrome can occur where use of arms and legs causes spasms. PMR is diagnosed when the clinical picture is present with an elevated mark of expansion (ESR and / or CRP). If temporal arteritis is suspected (headaches, changes in vision, limbs of lameness), temporal artery biopsy may be required to indicate vascular inflammation.
PMR and TA may show symmetric inflammatory arthritis similar to RA. These diseases can usually be distinguished by blood tests. In addition, headaches, changes in vision, large muscle pain are rare in RA, and PMR and / or TA need to be considered when these are present.
In the second part of this article we discuss the infections that need to be considered in the differential diagnosis of rheumatoid arthritis. When RA is suspected, it is important to consult a specialist rheumatologist.
