A 62-year-old man with asthma presented with a 1-month history of wheezing and exertional dyspnea. Although the wheezing symptoms disappeared after systemic corticosteroid therapy, the exertional dyspnea and hypoxemia did not improve. A diagnosis of intravascular large B-cell lymphoma (IVLBCL) with pulmonary involvement was suspected because of the increased serum lactic dehydrogenase (LDH) and soluble interleukin-2 receptor (sIL-2R) level, increased alveolar-arterial oxygen difference (AaDO2), decreased pulmonary diffusing capacity for carbon monoxide (DLCO) and scintigraphic, computed tomography (CT) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT findings. The patient was diagnosed as having IVLBCL with pulmonary involvement based on a pathological analysis of a random skin biopsy and a transbronchial lung biopsy. IVLBCL should be considered in patients with symptoms of asthma that are refractory to corticosteroid treatment.