A Dasatinib-Induced Chylothorax Persisting After the Discontinuation of Dasatinib

Dasatinib is a second-generation tyrosine kinase inhibitor with activity on the BCR-ABL fusion gene. It is used in the treatment of BCR-ABL positive chronic myeloid leukaemia and has the known side effect of pleural effusion. This usually involves exudate with the presence of lymphocytes. A more uncommon side effect is the development of a chylothorax. We describe a case of a 67-year-old man with chronic myeloid leukaemia, for which treatment with dasatinib, with the presence of a right-sided chylothorax. The man presented at an outpatient consultation due to complaints of exertional dyspnoea. Radiographic imaging showed the presence of a right-sided pleural effusion. Several punctures were performed with an evacuation of 4,900 mL bloody chylous fluid in total. Each puncture revealed an increased concentration of triglycerides on the fluid, hence confirming a recurring chylothorax. A pleurodesis was performed as a final therapy. Bosutinib was substituted for dasatinib eight months prior to initial admission, making this the first reported persisting dasatinib-induced chylothorax after discontinuation. The pathophysiology has not yet been fully elucidated; it is suspected to involve an interaction on the PDGFR-β pathway. LEARNING POINTS: Dasatinib is a rare cause of chylothorax. Chylothorax should be included in the differential diagnosis in patients developing pleural effusions when treated with dasatinib. The cornerstone of the treatment is tapering the dose or discontinuing the dasatinib therapy and changing it to another tyrosine kinase inhibitor.