Seronegative arthropathies are group of sero negative arthritis (negative rheumatoid factor) that share certain epidemiologic, clinical and pathologic features. They all show considerable overlap and similarity of articular and extra - articular clinical features.
• Ankylosing spondylitis.
• Reiter's disease.
• Psoriatic arthritis.
• Post infectious reactive arthropathies.
• Enteropathic arthropathies associated with:.
• Ulcerative colitis.
• Chron's disease
• Asymmetrical peripheral arthritis.
• Familial association.
• High prevalence with HLA- B27 .
• Negative rheumatoid factor.
• Uveitis.
• Aortic root fibrosis -» aortic incompetence.
• Erythema nodosum.
• Enthesitis i.e 'inflammation at the enthesis (the site of insertion of ligaments or tendons into bone).
• The invading organism in HLA - 827 initiates an autoimmune reaction or render the cells more susceptible to cytotoxic lymphocytes .
What are the variants of Seronegative arthropathies ?
They include :• Ankylosing spondylitis.
• Reiter's disease.
• Psoriatic arthritis.
• Post infectious reactive arthropathies.
• Enteropathic arthropathies associated with:.
• Ulcerative colitis.
• Chron's disease
General features of Seronegative arthropathies
• Sacroiliitis and / or spondylitis.• Asymmetrical peripheral arthritis.
• Familial association.
• High prevalence with HLA- B27 .
• Negative rheumatoid factor.
• Uveitis.
• Aortic root fibrosis -» aortic incompetence.
• Erythema nodosum.
• Enthesitis i.e 'inflammation at the enthesis (the site of insertion of ligaments or tendons into bone).
Why possession of HLA - B27 predispose towards seronegative arthropathies !?
• There is a cross reactivity between HLA - B27 and an antigen carried by some invading organisms e.g. yersinea, Chlamydia, klebsiella?• The invading organism in HLA - 827 initiates an autoimmune reaction or render the cells more susceptible to cytotoxic lymphocytes .