Oligoarthritis

Oligoarthritis - inflammation of 2-3 joints - is characteristic of a large number of diseases. To confirm the inflammatory nature of oligoarthritis, it is crucial to examine the cerebrospinal fluid with detection of high cytosis (>1000 in 1 μl), as well as the absence of radiographic changes characteristic of various non-inflammatory joint diseases (osteoarthritis, ischemic bone necrosis). Radiographic changes characteristic of oligoarthritis develop slowly, over months, the first of which is periarticular osteoporosis. The only exception is purulent arthritis (periarticular osteoporosis and signs of cartilage destruction in the form of narrowing of the joint space may appear within a few days).

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What causes oligoarthritis?

Oligoarthritis accompanied by fever (>38 °C)

Discussion of the septic nature of oligoarthritis is necessary only in rare cases (monoarthritis predominates in sepsis). Oligoarthritis may occur in staphylococcal sepsis, gonorrhea and brucellosis. The main diagnostic value is the anamnesis, general symptoms of intoxication (fever with chills, severe weakness, headache), very severe pain in the affected joints (including at rest), detection of the entry portal of infection and characteristic "extra-articular" symptoms (for gonorrhea - vesicular or papular rash with hemorrhagic contents). Of decisive importance for the diagnosis are the results of the cerebrospinal fluid examination (cytosis> 50,000 with a predominance of neutrophils); bacterioscopy with Gram staining and a positive culture result.

Non-infectious diseases that are always or in some cases accompanied by fever include Still's disease, reactive oligoarthritis, microcrystalline arthritis (gout and calcium pyrophosphate crystal deposition disease), RA, ARF, as well as oncological diseases that occur with paraneoplastic manifestations in the form of oligoarthritis.

Adult Still's disease

The main differential diagnostic value is the peculiar rash (non-itching, predominantly spotted, salmon-colored, appears at the peak of fever), significant leukocytosis of both peripheral blood and cerebrospinal fluid, high concentration of ferritin and normal level of procalcitonin in the blood.

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Reactive oligoarthritis

Characterized by a clear chronological connection (within 1-3 weeks) with a clinically expressed acute intestinal or urogenital infection (caused mainly by Chlmydia trachomatis); asymmetrical oligoarthritis of large and medium joints of the legs; enthesitis; dactylitis; sometimes also sacroiliitis, spondylitis, keratoderma, conjunctivitis. In some cases, fever may also accompany oligoarthritis developing with other seronegative spondyloarthritides (psoriatic arthritis, AS, oligoarthritis in chronic inflammatory bowel diseases).

Gout

Oligoarthritis (mainly of the joints of the lower extremities) is usually not the first manifestation of gout. Such patients usually have a history of recurrent acute monoarthritis. The main diagnostic value is the detection of urate crystals in the cerebrospinal fluid.

Calcium Pyrophosphate Crystal Deposition Disease

Pyrophosphate gout, pseudogout, chondrocalcinosis. Develops mainly in elderly people. Can be provoked by intercurrent infection, trauma, surgery. As a rule, knee joints are involved. Chondrocalcinosis is characteristic of both clinically affected and other joints (calcification of meniscus and articular cartilage). The diagnosis is confirmed by the detection of pyrophosphate calcin dihydrate crystals in the cerebrospinal fluid.

Rheumatoid arthritis

Oligoarthritis accompanied by fever is more characteristic of the seronegative variant of the disease.

Acute rheumatic fever

Of diagnostic importance are the chronological association with acute tonsillitis, pharyngitis and/or scarlet fever, very severe joint pain, the migratory nature of arthritis, signs of cardiac involvement and detection of serological markers of acute streptococcal infection. Poststreptococcal oligoarthritis without cardiac involvement is also possible.

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Oncological diseases

In adults, oligoarthritis is regularly observed in acute leukemia, chronic lymphocytic leukemia and some types of lymphomas (angioimmunoblastic lymphadenopathy). The following symptoms should be alarming in relation to hematological and lymphatic tumors: generalized enlargement of the lymph nodes, liver and spleen, persistent changes in the peripheral blood (anemia, hyperleukocytosis with a shift in the leukocyte formula to the left to immature forms, leukopenia, pancytopenia).

Of valuable, although not absolute value for distinguishing between bacterial infections occurring with oligoarthritis (except tuberculosis) and non-infectious arthritis accompanied by fever, are the results of determining procalcitonin and blood; an increase in the level of procalcitonin over 0.5 pg/ml most likely indicates a bacterial infection. A negative result of this test does not exclude the diagnosis of infection.

Persistent oligoarthritis without fever

Most patients are ultimately diagnosed with a disease from the group of seronegative spondyloarthritis or rheumatoid arthritis.

Diseases from the group of seronegative spondyloarthritis are characterized by predominantly asymmetrical lesions of large and medium joints of the legs, as well as additional signs, such as enthesitis (especially in the heel areas), arthritis of the distal interphalangeal joints of the hands, dactylitis (oligoarthritis in combination with tenosynovitis), lesions of the sternocostal joints, sacroiliitis, spondylitis, anterior uveitis, aortitis, aortic valve insufficiency, atrioventricular conduction disorders, psoriasis of the skin and nails, detection of HLA-B27, signs of Crohn's disease or nonspecific ulcerative colitis, the presence of diseases of this group in direct relatives. Most often, chronic oligoarthritis of this group of diseases is noted in patients with psoriasis. If spondyloarthritis is suspected, regardless of the clinical manifestations, an X-ray examination of the sacroiliac joints is indicated.

In rheumatoid arthritis, the involvement of 1-3 joints is usually only a relatively short-term phase of the disease. Over time (usually within the first year of the disease), inflammation of other joints joins in, including the small joints of the hands and feet.

How is oligoarthritis recognized?

To clarify the nosological diagnosis of oligoarthritis, the anamnesis and identification of changes in other organs and systems characteristic of various rheumatic, endocrine, metabolic and other diseases are of primary importance.

The role of synovial biopsy

In general, the diagnostic value of synovial membrane biopsy is small. As a rule, a regular morphological study does not provide more information than a full examination of the cerebrospinal fluid. Only in rare cases and sometimes only with the use of special stains, a synovial membrane biopsy can establish a previously unclear diagnosis, for example, in granulomatous diseases (sarcoidosis, tuberculosis), hemochromatosis (staining for iron according to Perls), Whipple's disease (staining with iodine reagent-Schiff), amyloidosis (staining with Congo red). As has been shown, a study of cerebrospinal fluid is more informative in microcrystalline arthritis, osteoarthrosis, and a synovial biopsy (under arthroscopy) - in synovial chondromatosis and hemangioma of the synovial membrane. However, it should be noted that a synovial biopsy is always desirable when there is a suspicion of joint diseases characterized by specific morphological changes (tuberculosis, sarcoidosis, amyloidosis), when it is not possible to confirm the diagnosis by less invasive methods. In addition, a synovial biopsy with subsequent microbiological examination is also indicated in cases where an infectious lesion of the joint is suspected in both acute purulent and chronic non-purulent arthritis, for example, in Whipple's disease, fungal oligoarthritis, etc.

X-ray and other imaging techniques

To determine the causes of oligoarthritis and to clarify the condition of the affected joints, radiography is mandatory. There are no radiographic signs that are pathognomonic for individual joint diseases, but changes that do not contradict or contradict inflammatory joint damage or that direct diagnostics in the right direction can be established.

• Suppurative oligoarthritis: rapid (in the first weeks) development of periarticular osteoporosis and narrowing of the joint space.
• Chronic non-suppurative oligoarthritis: the following sequence of development of radiographic changes is typical for RA: periarticular osteoporosis -> narrowing of the space -> marginal cysts and erosions. Deviations from this sequence (for example, the absence of periarticular osteoporosis in the presence of narrowing of the joint space) should be considered as a contradiction to this diagnosis.
• Oligoarthritis of peripheral joints in spondyloarthritis: periarticular osteoporosis may be absent, focal proliferation of osteoporotic tissue (around erosions, at the sites of attachment of the capsule and tendons), periostitis of the metaphyses or diaphysis may be observed.
• Psoriatic oligoarthritis: typical intra-articular and extra-articular osteolysis, multidirectional subluxations of bones; characteristic destruction of the distal interphalangeal joints of the hands.
• Gouty oligoarthritis: in chronic arthritis, intraosseous cysts and marginal erosions are possible both in the articulating parts of the bones and around the joint; periarticular osteoporosis is rare; changes are most often found in the joints of the big toes.
• Calcium pyrophosphate crystal deposition disease: typical chondrocalcinosis (menisci, articular cartilage), signs of secondary osteoarthrosis in combination with periarticular osteoporosis; chondrocalcinosis is most often localized in the knee joints, triangular cartilage in the wrist joints and cartilage of the pubic symphysis.

The main role of ultrasound of joints in diagnostics and differential diagnostics of oligoarthritis is to clarify the condition of joints that are difficult to directly examine (shoulder and hip). The method allows assessing the presence of effusion in the joint cavity, identifying pathology of tendons attached to the joint area (ruptures, tenosynovitis) and deep-seated bursae (bursitis).

X-ray CT allows to clarify the condition of mainly bone structures of joints. This study is especially valuable for diagnostics of those joint diseases in which primary changes are localized in bone tissue (tuberculosis, septic oligoarthritis due to osteomyelitis), as well as for differential diagnostics of oligoarthritis with bone tumors (for example, with osteoid osteoma).

MRI, unlike X-ray CT, is the most informative for visualizing the condition of soft tissues (cartilage, menisci, intra-articular ligaments, synovial membrane, tendons, synovial bags). In addition, MRI allows you to identify bone marrow edema. In this regard, it is used for early diagnostics of osteoarthritis, other diseases based on pathology of articular cartilage, ischemic bone necrosis, hidden bone fractures (stress fractures), sacroiliitis, to identify traumatic pathology of the menisci and cruciate ligaments of the knee joint, pathology of periarticular soft tissues.

Skeletal scintigraphy using bisphosphonates labeled with technetium-99m allows identifying areas of bone tissue where metabolism is enhanced (increased accumulation of radionuclide). In addition, this radiopharmaceutical accumulates in those joint tissues where blood flow is enhanced (for example, in the synovial membrane in arthritis). Due to its very high sensitivity and low specificity, this method is used mainly to obtain preliminary information about the localization of the pathological process. The nature of the detected changes usually requires further clarification using tomographic research methods.