Systemic lupus erythematosus — SCE Rheumatology MCQ

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EasyConnective Tissue DiseasesSystemic lupus erythematosusSCE Rheumatology

A 24-year-old woman has photosensitive rash, oral ulcers and inflammatory arthralgia. Urinalysis shows protein 1+ and microscopic haematuria. ANA is 1:1280, anti-dsDNA is positive and C3/C4 are low. She has no psoriasis or preceding infection. What is the most likely diagnosis?

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Correct answer: B — Systemic lupus erythematosus

Explanation lettering: D = shown as A · C = shown as B · E = shown as C · A = shown as D · B = shown as E

Systemic lupus erythematosus is best because photosensitivity, mucosal ulcers, immune serology, low complement and urinary abnormalities strongly support SLE. A is less suitable because dermatomyositis would feature proximal weakness and myositis-specific antibodies; B is less suitable because sarcoidosis would be supported by granulomatous organ disease rather than lupus serology; D is less suitable because Behçet syndrome causes recurrent oral and genital ulceration but not anti-dsDNA nephritis; E is less suitable because RA does not typically cause photosensitivity with low complement and anti-dsDNA positivity. Clinical pearl: falling complement and rising anti-dsDNA often track immune-complex SLE activity.

Reference: EULAR SLE recommendations 2023; BSR lupus guideline