The differential diagnosis for gastric SMARCA4-UT includes gastric undifferentiated or poorly differentiated carcinoma with SMARCA4 deficiency, neuroendocrine carcinoma (NEC), EBV-associated carcinoma with lymphoid stroma, lymphomas (including anaplastic large cell lymphoma), melanoma, germ cell neoplasms, NUT-midline carcinoma and so on. The gene discussed is SMARCA4; the disease is anaplastic large cell lymphoma.