Osimertinib-Induced Unilateral Diffuse Alveolar Hemorrhage in a Patient With Pulmonary Adenocarcinoma

A 70-year-old man with lung adenocarcinoma was admitted to our hospital due to progressive dyspnea, 4 months after osimertinib initiation. His chest radiograph and computed tomography revealed ground-glass opacities and consolidations dominantly in the upper left lung. He took neither antiplatelet nor anticoagulation agent. No abnormality in coagulation was detected. Bronchoalveolar lavage fluid (BALF) became serially and increasingly hemorrhagic, and confirmed the diagnosis of alveolar hemorrhage. After steroid pulse therapy and withdrawal of osimertinib, his condition gradually improved, accompanied by regression of ground-glass opacities and consolidations. Osimertinib causes not only interstitial pneumonia but also alveolar hemorrhage. The consolidations may spread not bilaterally, but be localized unilaterally. We have to keep this rare adverse event in mind, and consider immediate withdrawal of osimertinib and treatment with steroid. Increased lymphocytes in the BALF may be a potential indicator of sensitivity to steroid and favorable prognosis in diffuse alveolar hemorrhage.