D27-14 Shrinking Lung Syndrome in a Pediatric Patient With Systemic Lupus Erythematosus

Abstract Rationale Shrinking Lung Syndrome (SLS) is a rare pulmonary complication of systemic lupus erythematosus (SLE), characterized by dyspnea, elevated diaphragms, and restrictive spirometry without parenchymal disease. First described in the 1960s, it remains among the least recognized lung complications of lupus. While adult cases are documented, pediatric reports are rare. Proposed mechanisms include diaphragmatic myopathy, phrenic neuropathy, hypoinflation from pleuritic pain, surfactant dysfunction, and respiratory-muscle fatigue. Corticosteroids and immunosuppressants improve outcomes, though residual restriction may persist. We present a pediatric case highlighting diagnostic challenges, physiologic confirmation, and treatment response. Case Description A 14-year-old girl with newly diagnosed SLE was referred for pulmonary assessment despite no respiratory complaints. Her systemic features included arthralgia, low-grade fever, alopecia, and weight loss. The typical presentation of unexplained dyspnea was absent, and fatigue was attributed to systemic illness. However, spirometry and lung volumes revealed restriction. Chest X-ray showed a smaller right lung, right pleural thickening, and elevated hemidiaphragm. Pulmonary function tests confirmed restriction (FVC 63 % predicted, FEV₁ 61 %, TLC 56 %) with normal DLCO, excluding interstitial disease. Maximal inspiratory and expiratory pressures (MIP/MEP) were reduced, indicating respiratory-muscle weakness. Repeat PFTs confirmed the pattern. Diaphragm ultrasound showed reduced right-sided excursion, and echocardiography ruled out pulmonary hypertension. CT chest demonstrated normal parenchyma, no interstitial lung disease (ILD), and no pleural effusion. In this context of SLE with low lung volumes, elevated diaphragm, preserved diffusion capacity, and absence of ILD or PH, the findings were consistent with SLS. The patient received systemic corticosteroids and immunosuppressive therapy, with gradual improvement in exercise tolerance and lung function. Conclusions SLS is a diagnosis of exclusion requiring elimination of ILD, neuromuscular disease, pleural effusion, and PH. The combination of restrictive spirometry, normal DLCO, elevated diaphragm, and normal parenchyma should prompt consideration of SLS, even without classic dyspnea. Early use of PFT with MIP/MEP and diaphragm ultrasound aids diagnosis and monitoring. Prompt immunosuppressive therapy can reverse functional decline and prevent progression. Recognizing this rare entity in children broadens pediatric data and underscores multidisciplinary evaluation of lupus patients with subtle pulmonary findings. This abstract is funded by: None