Diagnostic Dilemma in a Case of Anti-PL-7 Antibody-Positive Interstitial Lung Disease: When Autoimmune Alveolar Proteinosis Masquerades as Anti-Synthetase Syndrome

Beili Liu; Chao Xu; Yuqian Liu; Runze Song; Danbei Diwu; Fanqi Wu

doi:10.1002/rcr2.70217

Diagnostic Dilemma in a Case of Anti-PL-7 Antibody-Positive Interstitial Lung Disease: When Autoimmune Alveolar Proteinosis Masquerades as Anti-Synthetase Syndrome

Respirol Case Rep. 2025 Jun 3;13(6):e70217. doi: 10.1002/rcr2.70217. eCollection 2025 Jun.

Authors

Beili Liu¹, Chao Xu², Yuqian Liu³, Runze Song⁴, Danbei Diwu¹, Fanqi Wu¹

Affiliations

¹ Department of Respiratory Medicine, The Second Hospital and Clinical Medical School Lanzhou University Lanzhou China.
² The Second Clinical Medical School Lanzhou University Lanzhou China.
³ Department of Anesthesiology, The Second Hospital and Clinical Medical School Lanzhou University Lanzhou China.
⁴ Department of Thoracic and Cardiovascular Surgery, The Second Hospital and Clinical Medical School Lanzhou University Lanzhou China.

Abstract

Pulmonary alveolar proteinosis (PAP) and anti-PL-7 antibody-positive interstitial lung disease (ILD) share early radiographic similarities, yet their treatments differ significantly. This article reports a rare case of dual anti-PL-7 and anti-GM-CSF autoantibody positivity, initially misdiagnosed as anti-synthetase syndrome due to interstitial infiltrates and concurrent Nocardia/Aspergillus infections. Empirical glucocorticoid therapy worsened symptoms. Definitive PAP diagnosis was confirmed via milky bronchoalveolar lavage fluid (BALF) and anti-GM-CSF autoantibody detection, alongside incidental pulmonary embolism. Multidisciplinary intervention (antimicrobials, thrombolysis, and whole-lung lavage) improved oxygenation. Clinicians must consider PAP as a differential diagnosis in patients with atypical presentations before commencing immunosuppressive therapy. Multidisciplinary collaboration is crucial for managing complex PAP cases.

Keywords: anti‐GM‐CSF autoantibody; anti‐PL‐7 antibody; multidisciplinary intervention; pulmonary alveolar proteinosis; steroid.