A46-01 An Unlikely Culprit: Thoracic Serositis Amid Inflammatory Bowel Disease

Abstract Introduction Inflammatory Bowel Disease (IBD) is a chronic condition characterized by systemic inflammation, with extra-intestinal manifestations affecting up to 40% of patients. While musculoskeletal and dermatological manifestations are most common, thoracic involvement is rare. Thoracic serositis may present as pleuritis, pericarditis, myopericarditis, or pleuropericarditis. This report describes the diagnostic challenges faced in the case of Crohn’s disease (CD) complicated by pleuropericarditis, and highlights the importance of considering serositis in the differential diagnosis of unexplained systemic inflammation in patients with IBD. Description A 41-year-old woman with well-controlled CD on vedolizumab presented with acute-onset sharp chest pain and dyspnea. Initial workup demonstrated elevated inflammatory markers, including ESR and CRP, but normal BNP and troponin levels, excluding primary cardiac injury. Rheumatologic serologies and autoimmune panel were negative. Echocardiography revealed a large pericardial effusion (2 cm) without signs of tamponade. CT chest showed chronic right pleural effusion and a new trace left pleural effusion. The patient was treated with colchicine and a tapering regimen of ibuprofen for suspected pericarditis, resulting in an interval reduction of the pericardial effusion (1-2 cm) on follow-up imaging after 2 months. However, the left pleural effusion increased in size, requiring thoracentesis. Fluid analysis showed a sterile, neutrophil-predominant exudate with a negative infectious workup. After excluding alternative etiologies, the pleuropericarditis in the setting of systemic inflammation was attributed to an extra-intestinal manifestation of CD. The patient was advised to continue colchicine therapy. Subsequent follow-up imaging at 4 months demonstrated radiographic improvement, and the patient’s symptoms resolved. Discussion Thoracic serositis is a rare pulmonary manifestation of IBD, less frequently encountered than airway or interstitial involvement. It is a diagnosis of exclusion that must be considered even when the underlying bowel disease is quiescent. Clinical presentation varies with the size of the effusion and the nature of pleural/pericardial manifestation. A thorough workup is needed to rule out an infectious, malignant, metabolic, or cardiac etiology. Shared embryogenesis is hypothesized to link respiratory disease and IBD, as the respiratory system originates from the foregut’s ventral wall. Thoracic involvement can occur at any stage of CD, sometimes preceding gastrointestinal symptoms. Diagnosis is often obscured due to the masking effects of immunosuppressive therapy commonly used in IBD. Patients generally respond well to anti-inflammatory treatment, underscoring the importance of early recognition that can help prevent serious cardiopulmonary complications. This abstract is funded by: None