Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 11 1 2025 01 01 109 112 Maryam Sarkhosh Department of Anesthesia, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran. Atiyeh Sadat Sajadi Department of Anesthesia, Allied Medical School, Iran University of Medical Sciences, Tehran, Iran. Omid Moradi Moghaddam Critical Care Medicine Department, Trauma and Injury Research Center, Iran University of Medical Sciences, Tehran, Iran. Parisa Moradi Majd Department of Anesthesia, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran. 2024 04 02 2024 04 24 Hemothorax, a condition characterized by blood accumulation in the pleural space, primarily results from trauma, affecting around 300,000 individuals annually in the United States. Spontaneous cases, although rare, pose diagnostic challenges due to diverse etiologies such as coagulation disorders, vascular anomalies, and neoplastic diseases. Diagnostic modalities like computed tomography, chest X-ray, and ultrasound play a crucial role in identification. A 29-year-old female with multiple sclerosis presented with severe chest symptoms, leading to pleural effusion requiring chest tube insertion. Despite inconclusive rheumatologic tests, evaluations excluded malignancies and thromboembolic events, enabling transfusions and supportive care. Global cases underscore varied causes of spontaneous hemothorax, with management strategies emphasizing interdisciplinary care. While certain conditions were ruled out, unresolved rheumatologic concerns persisted post-discharge, highlighting the need for further research to enhance diagnosis and management of spontaneous hemothorax. https://aacc.tums.ac.ir/index.php/aacc/article/view/968