Shared Features:
• HLA-B27 positive (varies by condition)
• Seronegative (RF and anti-CCP negative)
• Axial arthritis (especially sacroiliac joints)
• Enthesitis: inflammation at tendon insertions (e.g. Achilles, plantar fascia)
• Dactylitis: diffuse swelling of fingers/toes ("sausage digits")
• Anterior uveitis: painful red eye, photophobia, unilateral, recurrent
• Demographics: young men (<40 yrs), strong HLA-B27 association
• Symptoms:
o Insidious low back pain, improves with exercise/rest worsens
o Morning stiffness >30 mins
• Tests:
o Schober’s test: reduced lumbar flexion
o MRI SI joints: early sacroiliitis (detects inflammation before X-ray changes)
o X-ray: sacroiliitis → bamboo spine (syndesmophyte formation)
• Extra-articular features:
o Anterior uveitis
o Aortic regurgitation (aortitis)
o Apical pulmonary fibrosis (late)
o AV block (rare)
• Management:
o First-line: NSAIDs
o Exercise + physiotherapy
o Biologics: anti-TNF (e.g. etanercept) if inadequate response to NSAIDs
o DMARDs (e.g. sulfasalazine) only for peripheral joint involvement
• Occurs in 10–20% of psoriasis patients
• Joint patterns (can vary):
o Asymmetrical oligoarthritis (most common)
o DIP joint predominant
o Arthritis mutilans (severe destructive form)
o Symmetrical polyarthritis (mimics RA)
• Clinical features:
o Dactylitis
o Nail involvement: pitting, onycholysis
• X-ray: "Pencil-in-cup" deformity, periostitis
• Management:
o NSAIDs first-line
o DMARDs: methotrexate, sulfasalazine
o Anti-TNF if resistant or axial disease
• Cause: post-GI (Campylobacter, Shigella, Salmonella, Yersinia) or GU (Chlamydia) infection
• Classic triad: arthritis, urethritis, conjunctivitis
• Other features: keratoderma blennorrhagica, circinate balanitis
• Onset: 1–4 weeks post-infection
• Investigations:
o HLA-B27 positive (~70%)
o Exclude septic arthritis (especially in monoarthritis)
• Management:
o Treat underlying infection (e.g. doxycycline for Chlamydia)
o NSAIDs for arthritis
o Intra-articular steroids for persistent joint inflammation
• Occurs in patients with IBD (Crohn’s disease or ulcerative colitis)
• Patterns:
o Axial: sacroiliitis/spondylitis (independent of IBD activity)
o Peripheral: large joints (knees, ankles), parallels IBD activity
• Treatment:
o NSAIDs with caution (may worsen IBD)
o Sulfasalazine, biologics (anti-TNF agents like adalimumab)
————————————————————————————————————————————————————————————————————————————————————————————————————————-
Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
