Rheumatoid Arthritis

• A chronic systemic inflammatory disorder. • It can affect numerous tissues and organs, but it primarily affects the joints, causing a non-suppurative proliferative and inflammatory synovitis that frequently proceeds to articular cartilage degradation and joint ankylosis.

INCIDENCE

•Involves about 1% of the population

•Females are 3-5 times more affected than males

•Less common in African and Asian individuals but tends to be more aggressive.

•Majority of patients affected are 40-70 years old.

Genetic susceptibility • HLA-DRB 1 alleles

==Environmental arthritogen(==Causing or caused by arthritis)

• Microbial agents (i.e viral infections) have been implicated

• Citrullinated proteins (CCP)

Cause and pathogenesis

Autoimmunity • There is evidence for both abnormal humoral and cell-mediated immunity.

• These antibodies (usually IgM), which react with the Fc components of the IgG, can be detected in the blood as rheumatoid factor • Approximately 25 % of patients have antinuclear antibodies.

CLINICAL FEATURES

Swollen, tender and warm joints Symmetrical involvement ‘Morning stiffness’ is a common complaint .Any joint may be affected, mostly Small hand joints Feet joints Wrists, elbows and ankles are often involved. Insidious onset, chronic disease

Typical findings:

•chronic inflammation of the synovium

•exudation of cells, fluid, and fibrin (rice bodies) into the articular cavity

•erosion of cartilage

•juxta-articular osteoporosis

•bony ankylosis

•deformities of the joints

Extra-articular manifestations:

•subcutaneous rheumatoid nodules

•lymphadenopathy

•Splenomegaly and neutropaenia (Felty’s syndrome)

•anaemia

•dry mouth and dry eyes

•pneumonitis with interstitial fibrosis and nodules

•pericarditis

•uveitis and scleritis

morphology

symmetric athritis

• Synovium-oedematous, thickened, hyperplastic

-Main histologic features:

•synovial cell hyperplasia and proliferation

•dense inflammatory infiltrate

•increased vascularity due to angiogenesis

•fibrinopurulent exudate on synovial and joint surfaces

•osteoclastic activity in underlying bone

Pannus is A mass of oedematous synovium, inflammatory cells, granulation tissue that grows over the articular surface and causes its erosion

Fibrosing ankylosis is When cartilage has been destroyed and the pannus bridges the apposing bones

Bony ankylosis is Fusion of bones

h ![Early rheumatoid dâease. A byer of chronic inflammatory tisue (’pannus', arrowed) has eroded the a1!cuIar„ surface of the ferroral condyb.

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Rheumatoid Nodules • Develop in about 30% of patients with RA • Not diagnostic of RA

Gross morphology Firm, non-tender, round to oval • Located on ulnar surface of the forearm, elbow, lumbosacral area • Arise in subcutaneous tissue • Less commonly may be found in the lungs, spleen, pericardium, myocardium, heart valves and aorta

Histopathology • central area of fibrinoid necrosis • surrounding rim of macrophages, lymphocytes and plasma cells

MORPHOLOGY

Blood vessels

• Acute necrotising vasculitis (small and large arteries)

• Can involve pleura, pericardium, lung

• Obliterans endarteritis can occur obstructing digital arteries causing peripheral neuropathy.,ulcers, gangrene

• Leukocytoclastic vasculitis -produces purpura, cutaneous ulcers, nail bed infarction

• Ocular changes:uveitis, keratoconjuctivitis may be prominent.

RADIOLOGICAL FEATURES

• Osteopaenia

• Prominent radial deviation of the wrist

• Radial deviation of the fingers

• Flexion-hyperextension abnormalities of the fingers ( swan neck, botonniere)

• Marked loss of the joint spaces

• Erosions of the metacarpal and carpal bones

LABORATORY INVESTIGATIONS • Rheumatoid factor • Anti-CCP antibody • Normocytic normochromic anaemia • Raised ESR and CRP • Auto-antibodies such as ANF may be present

Rheumatoid factor • Found in only 75 % of patients with RA. • May be present in the serum of patients who do not have RA but who do have : • Systemic Lupus Erythematosus • Sjogren syndrome • infectious mononucleosis • viral hepatitis

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Juvenile Idiopathic Arthritis

• Variant of RA

• Begins before the age of 16 years

• There are several forms which correspond toseparate diseases and different backgrounds

• Long term prognosis is variable and 10 % of patients develop a serious functional disability

Several forms • systemic arthritis • oligoarthritis • rheumatoid factor-positive polyarthritis • rheumatoid factor-negative polyarthritis • rheumatoid factor polyarthritis • enthesitis • psoariatic arthritis • undifferentiated arthritis

Differences between JIA and adult RA

• Systemic disease is more frequent

• Large joints are affected more often than small joints

• Rheumatoid nodules and rheumatoid factor are usually absent

• Anti-nuclear antibody (ANA) seropositivity is common

Juvenile Stills disease / systemic arthritis

• Variant of JIA

• Abrupt onset

• Features include :

-high spiking fevers

-migratory and transient skin rash

-hepatomegaly

-serositis

• Associated with recurrent flares or persistent disease with significant morbidity