MRCP2-4357
A 67-year old male with metastatic small cell lung cancer presents with an acutely swollen leg. An ultrasound scan reveals a femoral vein deep vein thrombosis. Later in the day, he experiences pleuritic chest pain and SOB but neglects to inform the nursing staff. As his condition worsens, he becomes tachypnoeic and his oxygen saturation level drops to 88% on air. On auscultation, he has a wheeze bilaterally and reduced air on the left with hyper-resonant percussion note. An urgent CT thorax is requested, which shows a large 5 cm pneumothorax, bilateral segmental PE’s, left-sided 4x3x2 cm lung cancer (unchanged from last scan one month ago), and bibasal atelectasis. The patient stabilizes after a chest drain is inserted. What is the most likely cause of the pneumothorax?