Histology of Thoracic SMARCA4-UT gingival metastasis (magnifications x20). (A) Haematoxylin-eosin saffron (HES): trabeculae and solid nests of large rhabdoid cells (green arrow). Nuclei are large, clear, and nucleolated (red arrow). Large areas of necrosis (blue arrow). (B) No keratinization shown by immunohistochemistry AE1/AE3 using chromogenic detection with DAB (brown) and counterstain with hematoxylin (blue): immunonegativity for AE1/AE3 was observed in tumors cells (red arrow), normal epithelium cells (green arrow). (C) Mild heterogenous immunopositivity for EMA (brown), and occasionally dot-like in pattern (yellow arrow). (D) Mild heterogenous immunopositivity for Synaptophysin (brown).