MRCP2-2224

A 32-year-old man with normal cardiac and respiratory function is undergoing the ABVD chemotherapy regimen for his stage IIB Hodgkin’s lymphoma. He has successfully completed the first three cycles of chemotherapy without any complications. However, after finishing the fourth cycle, he complains of exertional dyspnoea and a dry cough. He has no fever, and his chest x-ray and ECG are normal. What is the most probable diagnosis?