To summarize, a large invasive mass involving the mediastinum, hilum, lungs, and/or pleura in young to middle-aged adults with a history of smoking, characterized by epithelioid/rhabdoid tumor cells, lacking both SMARCA4 and SMARCA2 expression, positive for SOX2, SALL4, and CD34, and negative for claudn-4 is a typical presentation of SMARCA4-UT. The gene discussed is SMARCA2; the disease is neoplasm.