Based on morphological, immunohistochemical, and statistical grounds, we conclude that the partial loss (mosaic expression) of SMARCB1 in SNSCC is associated with high-grade malignant characteristics and a negative effect on patient survival; meanwhile, SMARCA4-mosaic expression in SNSCC is associated with high-grade malignant characteristics and an increase in tumor size concerning the intact SMARCA4. This evidence concerns the gene SMARCB1 and neoplasm.