T-cell lymphoblastic lymphoma is a highly aggressive tumor derived from lymphocyte of the thymus, which accounts for 2% of non-Hodgkin's lymphoma. The disease occurs most commonly in adolescent and young adult males. It often results in respiratory emergency because of high proliferation rate. In this case, we confirmed the rapid progression of T-cell lymphoblastic lymphoma through the chest CT scan with one week interval. Three days of empirical chemotherapy resulted in substantial reduction of mediastinal mass, pleural thickening and pleural effusion.