Mixed connective tissue disease combines clinical features of systemic sclerosis, SLE, and polymyositis. It is associated with high titres of anti-U1-RNP antibodies. It is more common in women and peaks between 30 and 40 years of age. Systemic features System…

These autoimmune conditions overlap and may affect multiple organ systems. They are characterised by genetic predisposition → autoantibody production → immune complex deposition → chronic inflammation.

Polymyalgia Rheumatica is an inflammatory condition characterised by pain and stiffness of the shoulder, neck, and pelvic girdle. It frequently occurs with Giant Cell Arteritis (GCA). The symptoms respond quickly to treatment with oral corticosteroids. It rarely occurs in those…

Dermatomyositis is an autoimmune condition characterised by myositis and characteristic skin changes. It may be a paraneoplastic phenomenon – commonly from lung, pancreatic, ovarian, or bowel malignancy.

Polymyositis is an autoimmune-mediated inflammation of striated muscle. It is characterised by a slow onset of progressive symmetrical proximal muscle weakness, and myalgia +/- arthralgia.

Different antibodies have different disease associations Antibody Disease association Nota bene Rheumatoid factor (RF) Positive in Sjögren syndrome (≤ 100%), Felty’s syndrome (≤ 100%), rheumatoid arthritis (70%), mixed connective tissue disease (50%), hepatitis and infective endocarditis (<50%), SLE (≤ 40%),…

Ankylosing spondylitis is an autoimmune seronegative spondyloarthopathy that affects the axial skeleton and joints (shoulder and hip). It is HLA-B27 positive. It is more predominant in young men (under the age of 40), with a male-to-female ratio of 4:1.

Enteric arthritis is a seronegative spondyloarthopathy associated with gastrointestinal disease. Joint symptoms may precede bowel disease, occur simultaneously, or develop years later.

Reactive arthritis is a rare systemic inflammatory condition that follows gastrointestinal and urogenital infections. It presents with the triad of urethritis, conjunctivitis, and arthritis – “Can’t pee, can’t see, can’t climb a tree”. It is part of the seronegative spondyloarthropathies.

Psoriatic arthropathy is a chronic inflammatory, seronegative spondyloarthopathy associated with psoriasis. It occurs in 10-40% of patients with psoriasis and can present without skin changes. Classification of Psoriatic Arthropathy Classification Description Oligoarthritis Affects less than 5 joints and tends to be asymmetrical. This…