MUC5AC and signet ring cell carcinoma: (A) 7-class: carcinoma, tumor budding/poorly differentiated clusters, stroma, necrosis, mucin, smooth muscle, fat (B) 3-class: immature stroma, mature stroma, inflammatory stroma (C) 3-class: low grade carcinoma, high grade carcinoma, signet ring cell carcinoma (D) TILs identification