Rheumatology and Clinical Immunology
Expect pattern-based questions: a young woman with joint pain, an older patient with a headache and raised inflammatory markers, an acutely hot single joint, and a patient with rash, cytopenias and proteinuria. The skill tested is distinguishing inflammatory from mechanical disease and recognising the emergencies.
Inflammatory arthritis
- Rheumatoid arthritis: symmetrical small-joint swelling, morning stiffness over an hour, positive anti-cyclic citrullinated peptide and rheumatoid factor. Start methotrexate with folic acid early; check baseline liver enzymes, renal function and hepatitis B and C status. Add hydroxychloroquine or sulfasalazine before biologics.
- Axial spondyloarthritis: inflammatory back pain, sacroiliitis, HLA-B27 association, often with psoriasis or uveitis; first line is a non-steroidal anti-inflammatory drug plus physiotherapy.
- Do not use systemic steroids long term in rheumatoid arthritis; use bridging doses only.
Connective tissue disease and vasculitis
- Systemic lupus erythematosus: positive antinuclear antibody is sensitive but not specific; anti-double-stranded DNA and low complement track activity. Watch for lupus nephritis, which needs urine protein quantification and renal biopsy.
- Giant cell arteritis: new temporal headache, jaw claudication, visual loss, and high erythrocyte sedimentation rate in a patient over 50. Give high-dose glucocorticoid immediately, before biopsy, to protect vision.
- Antineutrophil cytoplasmic antibody vasculitis with pulmonary-renal syndrome is an emergency needing glucocorticoid plus cyclophosphamide or rituximab.
Crystal and septic arthritis
- Gout: negatively birefringent needle-shaped crystals; pseudogout: positively birefringent rhomboid crystals. Septic arthritis is the diagnosis to exclude; joint aspiration with cell count and culture is mandatory before assuming crystal disease.
Worked example
A 68-year-old woman reports two weeks of temporal headache and blurred vision, erythrocyte sedimentation rate 92 mm/h and C-reactive protein 88 mg/L. Start prednisolone 40-60 mg daily immediately, arrange temporal artery ultrasound or biopsy, and add bone protection and gastric cover. Do not wait for biopsy before steroids, because vision loss is irreversible.
Traps
Excluding septic arthritis on the basis of a normal peripheral white count; using antinuclear antibody titre to judge lupus activity; withholding steroids in suspected giant cell arteritis pending investigation; and forgetting hepatitis screening before methotrexate or biologic therapy.