MRCP Part 1 Rheumatology 3

Question 1

A 55-year-old man with gout whose serum urate is well controlled at 0.26 mmol/L on allopurinol develops an acute flare 2 months after his dose was increased. What is the most likely explanation?

Accepted Answer

Mobilisation of urate crystals during changes in serum urate

Answer

During initiation or dose adjustment of urate-lowering therapy, fluctuations in serum urate cause dissolution and mobilisation of existing crystal deposits, triggering acute flares despite adequate control.

Question 2

Joint aspirate from a swollen knee reveals rhomboid-shaped crystals that are weakly positively birefringent under compensated polarised light. How does this differ from the crystals found in gout?

Accepted Answer

Gout crystals are strongly negatively birefringent and needle-shaped

Answer

Calcium pyrophosphate crystals (pseudogout) are weakly positively birefringent and rhomboid-shaped, whereas monosodium urate crystals (gout) are strongly negatively birefringent and needle-shaped.

Question 3

A 10-year-old ANA-positive girl is diagnosed with oligoarticular juvenile idiopathic arthritis. Which potentially sight-threatening complication is classically asymptomatic and requires scheduled ophthalmological screening?

Accepted Answer

Anterior uveitis (iridocyclitis)

Answer

Anterior uveitis in oligoarticular JIA is often asymptomatic (no red eye, no pain) and can lead to irreversible blindness if undetected; regular slit-lamp examinations every 3–6 months are mandatory.

Question 4

A 28-year-old man of Turkish origin presents with recurrent painful oral ulcers, genital ulcers, inflammatory uveitis, and erythema nodosum. A pathergy test shows a pustule forming 48 hours after a needle prick. What is the most likely diagnosis?

Accepted Answer

Behçet's disease

Answer

Behçet's disease is a systemic vasculitis characterised by the triad of oral ulcers, genital ulcers, and uveitis, with a positive pathergy test; it is more prevalent along the ancient Silk Road including Turkey and the Middle East.

Question 5

A 33-year-old woman presents with puffy oedematous fingers, proximal muscle weakness, and pleuritis. Serology shows a very high-titre anti-U1 RNP antibody with no other specific autoantibodies detected. What is the most likely diagnosis?

Accepted Answer

Mixed connective tissue disease

Answer

Mixed connective tissue disease is defined by overlapping features of SLE, systemic sclerosis, and inflammatory myositis in the context of high-titre anti-U1 RNP antibodies as the sole specific autoantibody.

MRCP Part 1 Practice Test

MRCP Part 1 Practice Test

MRCP Part 1 Rheumatology 3