PLAB 1 Musculoskeletal Medicine & Rheumatology 2 — Questions and Answers
Question 1: A 58-year-old woman presents with proximal limb weakness, difficulty rising from a chair, and a heliotrope (violaceous) rash around her eyelids. Serum CK is markedly elevated. What is the most likely diagnosis?
- Polymyalgia rheumatica
- Dermatomyositis (Correct answer)
- Fibromyalgia
- Myasthenia gravis
Correct answer: Dermatomyositis
Dermatomyositis presents with proximal inflammatory myopathy, markedly elevated CK, and pathognomonic skin findings including the heliotrope rash and Gottron's papules.
Question 2: A 72-year-old woman presents with 3 months of bilateral shoulder and pelvic girdle aching and stiffness worse in the mornings, ESR 85 mm/hr, and CRP 45 mg/L. She responds dramatically to 15 mg prednisolone. What is the most likely diagnosis?
- Rheumatoid arthritis
- Fibromyalgia
- Polymyalgia rheumatica (Correct answer)
- Polymyositis
Correct answer: Polymyalgia rheumatica
Polymyalgia rheumatica presents in patients >50 years with bilateral girdle pain and stiffness, markedly elevated inflammatory markers, and a dramatic response to low-dose corticosteroids.
Question 3: Which important complication must all patients with polymyalgia rheumatica be warned about and screened for?
- Lupus nephritis
- Giant cell arteritis (Correct answer)
- Aortic valve disease
- Peripheral neuropathy
Correct answer: Giant cell arteritis
Giant cell arteritis occurs in 15–20% of PMR patients and can cause irreversible ischaemic visual loss; patients must be warned to report new headache, jaw claudication, or visual symptoms urgently.
Question 4: A 26-year-old man develops asymmetrical oligoarthritis, urethritis, and conjunctivitis 3 weeks after a confirmed Chlamydia trachomatis infection. What is this condition?
- Ankylosing spondylitis
- Reactive arthritis (Correct answer)
- Septic arthritis
- Psoriatic arthritis
Correct answer: Reactive arthritis
Reactive arthritis (formerly Reiter's syndrome) is a sterile inflammatory arthritis triggered by genitourinary or gastrointestinal infection, classically causing the triad of arthritis, urethritis, and conjunctivitis.
Question 5: A patient with rheumatoid arthritis on long-term methotrexate develops painful mouth ulcers and a macrocytic anaemia. Which supplement should be co-prescribed with methotrexate to prevent these side effects?
- Vitamin B12
- Folic acid (Correct answer)
- Ferrous sulphate
- Pyridoxine
Correct answer: Folic acid
Folic acid is routinely co-prescribed with methotrexate to reduce folate-deficiency side effects such as mucositis and macrocytic anaemia caused by methotrexate's folate antagonism.
Question 6: Which set of X-ray findings is characteristic of osteoarthritis, distinguishing it from inflammatory arthritis?
- Periarticular osteoporosis and soft tissue swelling
- Joint space narrowing, osteophytes, subchondral sclerosis, and cysts (Correct answer)
- Marginal erosions and periosteal reaction
- Chondrocalcinosis and uniform joint space loss
Correct answer: Joint space narrowing, osteophytes, subchondral sclerosis, and cysts
Osteoarthritis shows asymmetric joint space narrowing, osteophyte formation, subchondral sclerosis, and subchondral cysts — degenerative rather than erosive or inflammatory changes.
Question 7: A 40-year-old woman with limited cutaneous systemic sclerosis develops severe Raynaud's phenomenon and is found to have pulmonary arterial hypertension on echocardiography. Which antibody is most associated with this presentation?
- Anti-Scl-70 (anti-topoisomerase I)
- Anti-centromere antibody (Correct answer)
- Anti-dsDNA
- Anti-Jo-1
Correct answer: Anti-centromere antibody
Anti-centromere antibody is associated with limited cutaneous systemic sclerosis (CREST syndrome) and carries significantly increased risk of pulmonary arterial hypertension.
PLAB 1 Musculoskeletal Medicine & Rheumatology 2
A 58-year-old woman presents with proximal limb weakness, difficulty rising from a chair, and a heliotrope (violaceous) rash around her eyelids.
Serum CK is markedly elevated.
What is the most likely diagnosis?