Diagnosis of juvenile chronic arthritis

Laboratory diagnostics of juvenile rheumatoid arthritis

In the systemic variant of juvenile rheumatoid arthritis, leukocytosis (up to 30-50 thousand leukocytes) with a neutrophilic shift to the left (up to 25-30% of band leukocytes, sometimes up to myelocytes), an increase in ESR to 50-80 mm/h, hypochromic anemia, thrombocytosis, an increase in the concentration of C-reactive protein, IgM and IgG in the blood serum are often detected.

In the polyarticular variant, hypochromic anemia, slight neutrophilic leukocytosis (up to 15x10 ⁹ /l), ESR above 40 mm/h are detected. Sometimes a positive ANF is determined in the blood serum in a low titer. Rheumatoid factor is positive in the seropositive variant of juvenile rheumatoid arthritis, negative - in the seronegative variant. Serum concentrations of IgM, IgG, C-reactive protein are increased. In the seropositive variant of juvenile rheumatoid arthritis, HLA DR4 antigen is found.

In the oligoarticular variant with early onset, inflammatory changes in blood parameters typical of juvenile rheumatoid arthritis are sometimes detected. In some patients, laboratory parameters are within normal limits. In 80% of patients, a positive ANF is detected in the blood serum, the rheumatoid factor is negative, and the frequency of detection of HLA A2 is high.

In the oligoarticular variant with late onset, the clinical blood test reveals hypochromic anemia, neutrophilic leukocytosis, and an increase in ESR over 40 mm/h. Sometimes a positive ANF is detected in a low titer, and the rheumatoid factor is negative. Serum concentrations of IgM, IgG, and C-reactive protein are elevated. The frequency of detection of HLA B27 is high.

Determining the degree of disease activity based on laboratory parameters:

• 0 degree - ESR up to 12 mm/h, C-reactive protein is not detected;
• I degree - ESR 13-20 mm/h, C-reactive protein weakly positive (“+”);
• II degree - ESR 21-39 mm/h, C-reactive protein is positive (“++”);
• Grade III - ESR 40 mm/h or more, C-reactive protein sharply positive (“+++”, “++++”).

Instrumental methods

In the presence of myopericarditis, the ECG will show signs of overload of the left and/or right sections of the heart, impaired coronary circulation, and increased pressure in the pulmonary artery system.

EchoCG allows to detect dilation of the left ventricle, decreased left ventricular ejection fraction, hypokinesia of the posterior wall of the left ventricle and/or interventricular septum; signs of relative insufficiency of the mitral and/or tricuspid valves, increased pressure in the pulmonary artery; in pericarditis - separation of the pericardial leaflets, the presence of free fluid in the cavity.

X-ray examination of the chest organs reveals an increase in the size of the heart due to the left sections (less often total), an increase in the cardiothoracic index, an increase in the vascular-interstitial pattern of the lungs of a spotty-cellular nature, focal shadows. With fibrosing alveolitis in the early stages, an increase and deformation of the pulmonary pattern is revealed, with progression - stringy compactions, cellular enlightenment, a picture of a "honeycomb" lung is formed.

An important stage of the patient's examination is an X-ray examination of the joints.

Determination of the stage of anatomical changes (according to Steinbrocker):

• Stage I - epiphyseal osteoporosis;
• Stage II - epiphyseal osteoporosis, fraying of cartilage, narrowing of the joint space, isolated erosions;
• Stage III - destruction of cartilage and bone, formation of osteochondral erosions, subluxations in the joints;
• Stage IV – criteria of stage III + fibrous or bony ankylosis.

In addition, the functional class is determined (according to Steinbrocker).

• Class I: the functional capacity of the joints and the ability to self-care are preserved.
• Class II: the functional capacity of the joints is partially lost, the ability to self-care is preserved.
• Class III: the functional capacity of the joints and the ability to care for themselves are partially lost.
• Class IV: the functional capacity of the joints and the ability to care for themselves are completely lost.

Differential diagnosis of juvenile rheumatoid arthritis

Disease	Features of articular syndrome	Notes
Acute rheumatic fever	Polyarthralgia without visible changes in the joints; in rheumatoid arthritis, symmetrical damage to large joints of the lower extremities without deformations, is migratory in nature, quickly relieved by anti-inflammatory therapy with NSAIDs and corticosteroids; develops 1.5-2 weeks after acute streptococcal infection
Reactive arthritis	Develops 1.5-2 weeks after infectious diseases of the genitourinary organs caused by chlamydia, or diarrhea caused by yersinia, salmonella, shigella; asymmetrical damage to the joints, most often the lower extremities: knees, ankles, small joints of the feet; development of unilateral sacroiliitis, tendovaginitis of the Achilles tendon and plantar fasciitis, periostitis of the calcaneal tubercles	Yersiniosis can occur with fever, rash, arthralgia, arthritis, high laboratory activity indicators and can be a "mask" of the systemic variant of juvenile rheumatoid arthritis; yersiniosis is characterized by peeling of the skin of the palms and feet; a symptom complex that includes urethritis, conjunctivitis, arthritis, skin and mucous membrane lesions (nail dystrophy with keratosis, keratoderma on the soles and palms), the presence of HLA-B27, is called Reiter's disease
Psoriatic arthritis	Asymmetric oligo- or polyarthritis with damage to the distal interphalangeal joints of the hands and feet or large joints (knees, ankles); severe destructive (mutilating) arthritis develops with bone resorption, ankylosis; sacroiliitis and spondyloarthritis in combination with damage to peripheral joints	There are typical psoriatic changes in the skin and nails.
Juvenile ankylosing spondylitis	Lesions of the joints of the lower extremities (hip and knee)	Characterized by the presence of HLA B27, enthesopathies; symptoms of damage to the spine and sacroiliac joints usually appear after several years; characterized by progressive destruction of cartilage with ankylosis of the iliosacral joint
Systemic lupus erythematosus	In the initial period of the disease, polyarthralgia of a volatile nature and asymmetrical joint damage occur; at the height of the disease - symmetrical joint damage, not accompanied by erosions and persistent deformations, morning stiffness	Confirmed by the presence of typical facial erythema, polyserositis (usually pleurisy), nephritis, CNS damage, leukopenia and thrombocytopenia, lupus anticoagulant, ANF, antibodies to DNA, antiphospholipid antibodies
Systemic scleroderma	Arthralgia, developing into subacute or chronic arthritis, joints are affected symmetrically; the process involves small joints of the hands and wrists with minimal exudative manifestations, but pronounced compaction of soft tissues, development of flexion contractures, subluxations	Associated with characteristic skin and radiographic changes
Hemorrhagic vasculitis (Schonlein-Henoch disease)	Arthralgia or arthritis, unstable joint syndrome	Polymorphic, predominantly hemorrhagic rash on the lower extremities, large joints, buttocks; combined with abdominal and renal syndrome
Chronic ulcerative colitis and Crohn's disease	Peripheral asymmetric arthritis with predominant damage to the joints of the lower extremities; spondylitis, sacroiliitis; associated with the activity of the underlying disease	High detection rate of HLAB27
Tuberculosis	Severe arthralgia, spinal damage, unilateral gonitis, coxitis; diffuse osteoporosis, marginal bone defects, rarely limited bone cavity with sequestrum develop; destruction of articular ends of bones, their displacement and subluxations; reactive polyarthritis is also distinguished, developing against the background of visceral tuberculosis; damage to small joints is characteristic	Associated with positive tuberculin tests
Lyme disease (systemic tick-borne borreliosis)	Mono-, oligo-, symmetrical polyarthritis; possible development of cartilage and bone erosions	Combined with tick-borne erythema, damage to the nervous system, heart
Viral arthritis	The joint syndrome is short-term and completely reversible.	They occur in acute viral hepatitis, rubella, mumps, smallpox, arbovirus infection, infectious mononucleosis, etc.
Hypertrophic osteoarthropathy (Marie-Bamberger syndrome)	Deformation of fingers in the form of "drumsticks", hypertrophic periostitis of long tubular bones, arthralgia or arthritis with effusion into the joint cavity; symmetrical lesions of the distal joints of the upper and lower extremities (wrist, tarsus, knee joints)	Occurs in tuberculosis, fibrosing alveolitis, lung cancer, sarcoidosis
Hemophilia	Accompanied by hemorrhages in the joints with subsequent inflammatory reaction and effusion; the knee joints are affected, less often the elbow and ankle, wrist, shoulder and hip joints; comparatively rarely - the joints of the hands, feet and intervertebral joints	Begins in early childhood
Leukemia	Ossalgia, flying arthralgia, asymmetrical arthritis with sharp constant pain in the joints, exudative component and painful contractures	It should be excluded in systemic variants of juvenile rheumatoid arthritis
Neoplastic processes (neuroblastoma, sarcoma, osteoid osteoma, metastases in leukemia)	May be accompanied by myalgia, ossalgia, arthralgia, monoarthritis; characterized by severe pain syndrome in the periarticular areas, severe general condition that does not correlate with arthritis activity	Associated with typical hematological and radiological changes
Hypothyroidism	Arthralgia with slight soft tissue swelling and non-inflammatory effusion into the joint cavity; knee, ankle and hand joints are affected, carpal tunnel symptom may develop	Characterized by disturbances in skeletal formation, slow growth of long tubular bones and ossification, osteoporosis, muscle weakness, myalgia
Septic arthritis	It begins acutely; it often occurs as monoarthritis, with severe intoxication, increased temperature, and acute phase inflammation indicators, which is not typical for early-onset oligoarthritis.

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