Spontaneous haemothorax due to a non-invasive mediastinal thymoma

A male patient in his late 60s presented with sudden-onset chest pain, dry cough and exertional dyspnoea. He had a history of renal cell carcinoma treated with nephrectomy 10 years ago, and a biopsy-proven benign anterior mediastinal mass, thymoma, diagnosed 7 years earlier, for which he denied surgical resection and was lost to follow-up. Imaging revealed a large anterior mediastinal mass with associated left-sided moderate pleural effusion. Image-guided biopsy of the mass confirmed it to be type A thymoma. Thoracoscopy showed normal pleura with haemothorax. Positron emission tomography-CT scan ruled out local invasion and distant spread. A diagnosis of spontaneous haemothorax, likely due to ruptured mediastinal thymoma, was considered. The patient underwent successful video-assisted thoracoscopic surgery resection of the mass, and intraoperative findings confirmed bleeding from the ruptured tumour surface as the source of haemothorax. Postoperatively, the patient recovered uneventfully. This case highlights a rare but important complication of thymoma—spontaneous haemothorax even in non-invasive mediastinal tumours.