Background: Systemic lupus erythematosus (SLE) is a chronic inflammatory connective tissue disorder with multi-organ involvement. A rare complication of SLE is shrinking lung syndrome (SLS), characterized by progressive exertional dyspnoea, reduced lung volumes, and diaphragmatic elevation. Case Presentation: We report a case of SLS secondary to SLE, who required an extensive work up to exclude other more common causes of lung involvement in such a condition. This case report highlights the disease burden of SLS in a once active, independent young lady requiring nocturnal non-invasive ventilation (NIV) to relieve shortness of breath in a recumbent position. This patient had the triad of hypoxia at rest, type 2 respiratory failure, and diaphragmatic palsy. Several different immunomodulators were used initially with little success and it was not until she received six cycles of intravenous cyclophosphamide, that she no longer required NIV support, displayed improvements in pulmonary function tests and diaphragmatic motility and attained a normal lifestyle. Conclusion: The use of immunomodulators appeared to be particularly effective in restoring normal functional capacity in shrinking lung syndrome. However, the pathophysiology of this condition requires further studies.

Keywords: Systemic lupus erythematosus (SLE), dyspnoea, diaphragmatic elevation, shrinking lung syndrome (SLS), immunomodulators, cyclophosphosphomide, case report, hydroxychloroquine (HCQ), mycofenolate mofetil (MMF)