Thrombocytopenia as an Immune-Related Adverse Event in Malignant Pleural Mesothelioma: A Case Report

A 69-year-old man presented with a pulmonary opacity at a regular medical check-up. He had been exposed to asbestos in a chemical fiber manufacturing setting. Result of positron emission tomography with computed tomography (CT) revealed fluorodeoxyglucose accumulations along the right pleura in areas with multiple nodules and irregular pleural thickening. On the basis of analysis of a CT-guided needle biopsy result, he had been diagnosed with having epithelioid malignant pleural mesothelioma. He received neoadjuvant chemotherapy, and subsequently, a pleurectomy and decortication. After 6 months, malignant pleural mesothelioma recurred with multiple tumors in the pleural cavity. Nivolumab was administered as salvage immunotherapy. A CT scan result revealed marked tumor reduction; however, his platelet count was low (8000/μL), and he was diagnosed with having nivolumab-induced immune thrombocytopenia. Oral prednisone and thrombopoietin receptor agonist were delivered, and the platelet count improved; therefore, a sustained cycle of nivolumab was resumed. This case revealed that nivolumab could be readministered for continued antitumor effects, with careful management of immune-related adverse events.