In contrast to SMARCB1-deficient carcinomas, and because of their cell morphology and immunophenotype, most SMARCA4-deficient tumors have been initially misclassified as small or large cell neuroendocrine carcinomas and, less frequently, as SNUC or teratocarcinosarcoma [32, 33]. The gene discussed is SMARCB1; the disease is large cell neuroendocrine carcinoma.