Background: Cell blocks (CBs) from pleural fluid are frequently used in the practice of respiratory medicine, but there have been few reports on the use of CBs from forceps and brush washing fluid in bronchoscopy for pathological diagnosis. We retrospectively analyzed the usefulness of CBs from forceps and brush washing fluid. 　Patients and Methods: Patients who underwent bronchoscopy and had CBs made from forceps and brush washing fluid in bronchoscopy at our institution between June 2016 and May 2021 were included. Cases in which additional information was obtained from CBs were reviewed in detail. 　Results: In total, 138 patients had CBs made from forceps and brush washing fluid in bronchoscopy during the study period. EBUS-GS (endobronchial ultrasound-guide sheath) was used for 102 of these patients. The final diagnosis was lung cancer in 114 cases, infection disease in 10 cases, metastatic lung tumor in 8 cases, lymphoproliferative disease in 2 cases, sarcoidosis in 1 case, and organizing pneumonia in 1 case. There were 13 cases with additional information obtained from CBs, all of which were cases of malignant tumors. 　Conclusions: CBs from forceps and brush washing fluid in bronchoscopy were useful for pathological diagnosis in some cases.

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is useful for diagnosing mediastinal lymph node lesions. Cell blocks prepared from the needle washing fluid and flow cytometry of tissue samples are helpful in making the diagnosis, but the combination of both examinations is not routinely performed. A 77-year-old woman with fever, dyspnea, and anorexia was admitted to our hospital. Computed tomography showed enlarged mediastinal lymph nodes with calcification and left ureteral calculus; however, no focus of infection was identified. We suspected lymph node tuberculosis or malignant lymphoma, and EBUS-TBNA was performed to evaluate the mediastinal lymph node lesions. Because a cell block prepared from the needle rinse fluid was suspicious for malignant lymphoma, we changed the puncture needle from 22 G to 19 G and performed a second EBUS-TBNA. Diffuse large B-cell lymphoma (DLBCL) was diagnosed based on the results of flow cytometry of the EBUS-TBNA samples. Here we report this case of DLBCL in which mediastinal lymph node tuberculosis was suspected and cell block preparation and flow cytometry using EBUS-TBNA specimens were useful for the diagnosis.