A case of lung intravascular large B cell lymphoma developed with respiratory failure rescued by corticosteroid prior to definite diagnosis.

A 56-year-old man complained progressive dyspnea, fatigue and fever for one month. His chest CT exhibited faint ground-glass opacities, and the levels of serum LDH and soluble interleukin 2 receptor were markedly elevated. Positron emission tomography (PET) showed high uptake of 18-fluoro deoxy glucose (FDG) only on both lungs. We performed transbronchial lung biopsies (TBLB) for the diagnosis. After bronchoscopy, he had prolonged hypoxemia. Because defects of 99m-Technetium macroaggregated albumin (Tc-MAA) in pulmonary blood flow scintigraphy were consistent with the distribution of FDG uptake in PET, we speculated that the presence of intravascular lymphoma (IVL) cells in the capillaries might have behaved like tumor embolism. We started rescue by prednisolone based on treatment of lymphoma. As a result, his hypoxemia was gradually improved. Histological findings in TBLB specimen showed that CD20CD79Bcl-2c-myc lymphoma cells were localized to small vessel lumina in alveoli and bronchioles, and he was definitely diagnosed with lung intravascular large B cell lymphoma (IVLBCL). He was treated with complete cyclophosphamide, doxorubicin, vincristine, and prednisolone with rituximab (R-CHOP) in combination with intrathecal methotrexate injection. After eight cycles of R-CHOP and three times of intrathecal methotrexate, FDG uptake of PET on both lungs completely disappeared, achieving complete metabolic remission. We experienced a rare case of lung IVLBCL developed with respiratory failure successfully rescued by prednisolone prior to definite diagnosis.