Histopathological study of small (<2 cm) gastric carcinoma with signet-ring cell component: significance of the admixed glandular components.

Admixture of signet-ring cell carcinoma component (SIG) and glandular component (GC) is sometimes found in a gastric cancer. The aim of this study was to elucidate the biological behavior of the gastric cancer containing either SIG only (SIG-type tumor) or SIG admixed with GC (SIG-GC-type tumor). Forty-three cases of SIG-type tumor and 26 cases of SIG-GC-type tumor, less than 2 cm in largest diameter, were examined. Twenty-six cases (60%) of SIGs were less than 10 mm in size, whereas only 3 cases (12%) of SIG-GCs were less than 10 mm in size (p<0.0001). Submucosal invasion by cancer cells was found in 12 cases of SIG-GCs but was not found in any of the SIGs. Those SIG-GCs showed gastric phenotype. It is important to note SIG-GC-type tumor for histopathological diagnosis.