Massive Haemothorax Following CT-Guided Lung Biopsy Revealing Previously Undiagnosed Acquired Haemophilia A.

CT-guided lung biopsy is a commonly performed procedure with recognised complications, including pneumothorax and pulmonary haemorrhage. Massive haemothorax following biopsy is rare and may indicate an underlying coagulopathy. We present the case of a 75-year-old man who developed a life-threatening haemothorax following a CT-guided biopsy of a left lower lobe lung lesion. Despite initial haemodynamic stability, the patient's clinical course required transfusion, pulmonary artery embolisation, chest drainage, and video-assisted thoracoscopic surgery (VATS). The development of spontaneous iliopsoas and quadriceps haematomas during admission prompted further haematological investigation, which revealed previously undiagnosed acquired haemophilia A (AHA). This report highlights the importance of recognising disproportionate bleeding following interventional procedures and maintaining a low threshold for investigating occult bleeding disorders. Early multidisciplinary involvement was essential in achieving a favourable outcome.