Differences between gastric signet-ring cell carcinoma and poorly differentiated adenocarcinoma: A comparison of histopathologic features determined by mucin core protein and trefoil factor family peptide immunohistochemistry

We investigated differences between the pathological features of gastric signet-ring cell carcinoma (sig) and poorly differentiated adenocarcinoma (por) by examining the expressions of the trefoil factor family peptides (TFFs) and mucin core proteins (MUCs). Ninety-seven tissues of 97 gastric cancer patients were selected for this study. After gastrectomy, the major histopathologic types were determined to be sig, solid-type poorly differentiated adenocarcinoma (por1), non-solid type poorly differentiated adenocarcinoma (por2), and well-differentiated tubular adenocarcinoma (tub1). We evaluated the prevalence of positive staining for MUCs (MUC5AC and MUC2) and TFFs (TFF1 and TFF3) and assessed the correlation between MUCs and TFFs in each histopathological type. The rate of MUC2 expression significantly differed between sig and por2 (50.0% vs 11.7%, P = 0.011). TFF3 expression in sig significantly differed from TFF3 expression in both por2 (100% vs 17.6%, P < 0.0001) and por1 (100% vs 33.3%, P = 0.0004). MUC5AC and TFF1 expressions were significantly correlated in por1 (r = 0.705, P = 0.002), por2 (r = 0.535, P = 0.0009), and tub1 (r = 0.470, P = 0.0034), while MUC2 and TFF3 expressions were significantly correlated only in sig (r = 0.593, P = 0.040). The expression and correlation patterns of the TFFs and MUCs suggest that the histopathologic features of gastric sig differ from those of por.