B35-36 A Case of Shrinking Lung Syndrome Secondary to Systematic Lupus Erythematosus

Introduction Shrinking Lung Syndrome (SLS) is a rare complication of systemic lupus erythematosus (SLE) characterized by the development of dyspnea and in some cases, pleuritic chest pain. Workup often shows elevated diaphragm without parenchymal lung abnormalities, reduced lung volumes, and restrictive patterns on pulmonary function tests (PFTs). It has also been reported in other autoimmune diseases including rheumatoid arthritis, scleroderma, and Sjogren syndrome. Although various postulations have been made about the pathophysiology of SLS, its exact mechanism is still unknown. The prevalence is estimated to be around 1% and can occur at any point in the disease (Colquhoun & Akram, 2023). Most cases have a progressive course and can cause significant morbidity. Case Presentation We present a case of a 44-year-old female with a history of SLE which was diagnosed in 2016 after she presented with arthralgia, malar rash, and positive ANA (1:640) and anti-dsDNA antibodies. She was initially treated with corticosteroids and hydroxychloroquine with good symptom control. However, in 2017, her medications were escalated to mycophenolate and higher steroid doses after she developed lupus nephritis (Class IV) confirmed by kidney biopsy. In early 2018, she started experiencing subacute onset progressive exertional dyspnea. It was initially attributed to deconditioning but her symptoms worsened over several months. PFTs revealed restrictive lung disease with markedly reduced (31% predicted) forced vital capacity (FVC), and her CT scan of the chest showed bilateral hemidiaphragm elevation without parenchymal abnormalities. Other causes including infection, pulmonary hypertension, and interstitial lung disease were excluded and the shrinking lung syndrome (SLS) diagnosis was made. She was started on aggressive immunosuppressive therapy including rituximab, mycophenolate, and corticosteroids. Additionally, she underwent pulmonary rehabilitation. Over the next year, she had significant improvement in her symptoms and her pulmonary function testing, with the last FVC measured at 73% predicted. Discussion This case illustrates a rare complication of SLE that responded favorably to aggressive immunosuppression. It also highlights the importance of maintaining a high index of suspicion for this rare pulmonary sequala of SLE especially when other common etiologies have been ruled out. References Colquhoun M, Akram S. Shrinking Lung Syndrome. [Updated 2023 Feb 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK568683/ This abstract is funded by: None