skip to main content

Anti-PL-12 ILD — SCE Rheumatology MCQ

Instant feedback + full explanation. One question, done properly.

HardAutoimmune SerologyAnti-PL-12 ILDSCE Rheumatology

A 42-year-old woman has established systemic lupus erythematosus, previously manifested by biopsy-proven lupus nephritis and anti-Sm antibodies. Her lupus is clinically and serologically quiescent, but she develops progressive exertional dyspnoea. High-resolution CT shows fibrotic non-specific interstitial pneumonia with areas of organising pneumonia. Creatine kinase is normal and there is no objective muscle weakness. Extended myositis serology shows strong anti-PL-12 positivity, confirmed on a second assay. Which interpretation is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Anti-PL-12 antisynthetase syndrome overlapping with SLE, with an ILD-predominant amyopathic phenotype

Anti-PL-12 targets alanyl-tRNA synthetase and is an antisynthetase antibody. Compared with anti-Jo-1, anti-PL-12 is particularly associated with an ILD-predominant phenotype in which clinically apparent myositis may be absent; normal creatine kinase and strength therefore do not exclude antisynthetase syndrome. In a patient with independently established SLE, this is best interpreted as antisynthetase syndrome overlap rather than SLE-associated ILD alone. Inclusion body myositis is not defined by anti-PL-12 and rarely presents with autoimmune ILD. Anti-MDA5 identifies a different clinically amyopathic dermatomyositis phenotype and is not inferred from anti-PL-12. Clinical myositis is not mandatory when a confirmed antisynthetase antibody accompanies a characteristic manifestation such as ILD.

Reference: Pinal-Fernandez I, et al. A longitudinal cohort study of the anti-synthetase syndrome: increased severity of interstitial lung disease in black patients and patients with anti-PL7 and anti-PL12 autoantibodies. Rheumatology (Oxford). 2017;56:999-1007. https://pubmed.ncbi.nlm.nih.gov/28339994/