[Clinicopathological and genetic analysis of interstitial disease-like pulmonary intravascular large B cell lymphoma]

Objective: To investigate the clinicopathological features and genetic mutation status of pulmonary intravascular large B cell lymphoma. Methods: The clinicopathological data of eight patients diagnosed with pulmonary intravascular large B cell lymphoma, from April 2018 to May 2023, were retrospectively analyzed. The genetic profile of six patients was detected via next-generation sequencing (NGS) and followed up. Results: All patients included one male and seven females, with a median age of 64 years (ranging from 45 to 66 years). Respiratory symptoms were the most common (7 cases), B symptoms in two cases, hemophagocytic syndrome in two cases. Multiple diffuse ground-glass opacities in both lungs were observed based on the high-resolution chest CT scan. Six cases of mild to moderate ventilation or diffusion dysfunction were observed based on the pulmonary function tests. Moreover, two cases of hypoxemia and two cases with type Ⅰ respiratory failure were recorded. The serum lactate dehydrogenase level increased (7/8), β2-MG level increased (2/8), neuron-specific enolase level increased (7/8), total number of peripheral blood lymphocytes decreased (7/8), and clinical stages were all stage Ⅳ. The neoplastic lymphoid cells were lodged in the lumina of venules and capillaries of the alveolar septum; the tumor cells were large, with prominent nucleoli and frequent mitotic figures. The malignant cells were detected in the extravascular surrounding lung tissue in all cases. The tumor cells expressed mature B cell-associated antigens CD20 and CD79a, and the vascular endothelial markers CD31 and CD34 showed that the tumor cells were filled in the blood vessels, infiltrated blood vessel walls, and perivascular areas. One case was germinal center-type, seven cases were non-germinal center-type, two cases were double-expressing lymphoma, and all cases were EBER-negative. Furthermore, the top five genes with mutation frequencies detected by NGS were MYD88 (5/6), PIM1 (5/6), CD79B (4/6), TCF3 (4/6), and TP53 (3/6). Of the eight cases, seven patients received R-CHOP-based chemotherapy, six cases had complete remission after chemotherapy, one case died, and one case was lost to follow-up. Conclusions: Pulmonary vascular large B cell lymphoma is rare, which shares similar patterns with interstitial lung disease on imaging. Transbronchial lung biopsy is an effective method to confirm the diagnosis. Immunochemotherapy with BTK inhibitors can provide a survival advantage for patients in the future based on molecular typing.