[Case of precursor T-lymphoblastic lymphoma/leukemia diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration].

: An 18-year-old man was found to have a mediastinal tumor on a chest X-ray film. Chest CT demonstrated a large tumor in the anterior mediastinum. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of the mediastinal tumor was performed. The microscopic appearance of EBUS-TBNA and bone marrow revealed identical findings. Immunohistochemical staining of these specimens were positive for both CD3 and terminal transferase (TdT). Therefore, a diagnosis of precursor T-lymphoblastic lymphoma/leukemia was made. To the best of our knowledge, there are no studies which report that EBUS-TBNA is useful in the diagnosis of precursor T-lymphoblastic lymphoma/leukemia, but EBUS-TBNA was useful in the diagnosis of mediastinal tumor in this case. It may also be useful in the diagnosis of hilar or mediastinal lymphadenopathy in hematological disorders such as precursor T-lymphoblastic lymphoma/leukemia.