Morphogenesis of joint involvement
The disease is based on an immunopathological process affecting the synovial membrane. The main stages include:
- Synovitis: characterized by synoviocyte hyperplasia, formation of lymphoid aggregates (CD4+ T cells, plasma cells), and productive vasculitis.
- Pannus formation: aggressive granulation tissue that creeps over the cartilage, causing its erosion and replacement by fibrous tissue.
- Bone changes: development of osteoporosis, formation of subchondral cysts and erosions, ultimately leading to ankylosis.
Stages of arthritis development
The process goes through three consecutive stages:
- Early stage: dominated by edema, hemorrhages, and fibrinoid swelling. "Rice bodies" (necrotic villi) and ragocytes appear in the joint cavity.
- Intermediate stage: active pannus proliferation, deep cartilage destruction, formation of erosions (usures) and deformities such as ulnar deviation.
- Terminal stage: ends with the formation of fibrous-bony ankyloses, leading to complete loss of joint mobility.
Systemic manifestations (visceropathies)
Extra-articular changes due to connective tissue disorganization are observed in 20–25% of patients:
- Rheumatoid nodule: a specific lesion with a center of fibrinoid necrosis, surrounded by macrophages and lymphocytes.
- Organ involvement: polyserositis, vasculitis, glomerulonephritis, renal amyloidosis, fibrosing alveolitis, and myocarditis frequently develop.
- Immune system: characterized by lymph node and splenic hyperplasia with pronounced plasmacytosis.
Briefly: answers to topical questions
What are ragocytes, which appear in the joint in the early stage of rheumatoid arthritis?
Ragocytes are neutrophils in the serous effusion of the synovial fluid containing rheumatoid factor. These cells are characteristic of the first (early) stage of rheumatoid arthritis. Ragocytes secrete inflammatory mediators.
What types of hand finger deformities develop in the intermediate stage of rheumatoid arthritis?
In the intermediate and final stages of rheumatoid arthritis, the following typical hand finger deformities develop:
- Ulnar deviation — deviation of the fingers toward the ulnar side, forming a "walrus fin" appearance.
- Boutonnière deformity ("buttonhole") — flexion at the proximal interphalangeal joint and hyperextension of the distal interphalangeal joints.
- Swan-neck deformity — flexion contracture of the metacarpophalangeal joints, hyperextension of the proximal interphalangeal joints, and flexion of the distal interphalangeal joints.
- Lorgnette deformity — complex flexion contracture of the fingers with multiple subluxations.
- Z-shaped deformity of the thumb — subluxation in the interphalangeal joints.
What is rheumatoid factor and to which class of immunoglobulins does it most commonly belong?
Rheumatoid factor is an autoantibody reacting with the Fc fragment of immunoglobulin G (IgG). Most commonly, rheumatoid factor belongs to the IgM isotype; IgG, IgA, and IgE isotypes are less common. In the synovial membrane, plasma cells produce rheumatoid factor, and the antibodies interact with each other, with one of them acting as an antigen, which maintains inflammation in rheumatoid arthritis.
What triad of clinical and morphological features is characteristic of Felty's syndrome?
Felty's syndrome is characterized by the following symptom complex developing against the background of long-standing seropositive rheumatoid arthritis:
- Severe joint damage.
- Persistent granulocytopenia — less than 2000/mm³.
- Splenomegaly — enlargement of the spleen.
The syndrome is accompanied by a high risk of infectious processes.
"PAN-AS": Pannus, Ankylosis, Nephritis (amyloidosis), Synovitis.
Class and exam questions
What are "rice bodies"?
These are dense casts formed in the joint cavity from synovial villi that have undergone fibrinoid necrosis.
What is the role of pannus in pathogenesis?
Pannus is a layer of granulation tissue that actively destroys and replaces articular cartilage, leading to erosions and subsequent ankylosis.
What kidney changes are the most dangerous?
The most serious complication is renal amyloidosis (deposition of AA amyloid), which can lead to chronic renal failure.
What else to study on this topic
- Immunohistochemical composition of lymphoid aggregates in the synovium.
- Mechanisms of secondary amyloidosis development in rheumatoid arthritis.
- Differential diagnosis of rheumatoid nodules and rheumatic granulomas.
- Pathogenesis of vasculitis in systemic manifestations of the disease.
- Features of cardiac conduction system involvement in rheumatoid arthritis.
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