Pulmonary microvascular cytology can detect tumor cells of intravascular lymphoma.

A 68-year-old man was admitted to our hospital for indistinct consciousness, progressive dyspnea, night sweats and fever of 2 weeks duration. Hypoxemia, thrombocytopenia, and elevated serum lactate dehydrogenase were found. Computed tomography was negative except for a small bilateral pleural effusion. Chest perfusion scintigraphy showed inhomogeneous perfusion thought unlikely to be pulmonary artery thromboembolism. Intravascular large B-cell lymphoma was suspected, and a pulmonary microvascular cytology specimen was obtained that contained numerous large lymphoma cells. Because the patient's condition was rapidly deteriorating, we started chemotherapy on the basis of the pulmonary microvascular cytology findings, and he improved. Later, atypical lymphocytes similar to those in the pulmonary microvascular cytology specimen were found in a bone marrow specimen. He was diagnosed as having diffuse large B-cell lymphoma. Because lymphoma cells were found in the pulmonary microvasculature, intravascular lymphoma was also diagnosed. Pulmonary microvascular cytology was helpful to detect lymphoma cells in the pulmonary microvasculature.