Clinicopathologic Study on Poorly Differentiated Gastric Carcinoma with Medullary Growth Pattern

One hundred and sixty-nine cases of poorly differentiated gastric carcinoma with medullary growth pattern were investigated clinicopathologically regarding their histologic features and histochemical findings. They could be histologically subdivided into the following four types: 1) solid type (97 cases), 2) acinar type (54 cases), 3) undifferentiated type (12 cases), and 4) lymphoid stroma (6 cases). Solid type tumors had higher incidences of hepatic metastasis and lymph node metastasis than acinar type tumors. Moreover, the 5-year survival rates after surgery were 49.1% and 75.5% for solid type and acinar type tumors, respectively, showing that the prognosis for solid type tumors is significantly poorer than that for acinar type tumors. In many cases, acinar type tumors as well as lymphoid stroma tumors were accompanied by abundant infiltration of lymphocytes. Of the solid type tumors, there were 11 (11.3%) with argyrophil Grimelius stain-positive cells considered to differentiate into endocrine cells, and 17 (17.5%) with AFP-positive cells. The prognoses for these tumors were poor because of the frequent occurrence of hepatic metastasis after surgery. There was not a significant correlation between c-erbB-2 proteinstaining status and the prognosis for the patients. Thus, a wide variety of tumors were observed within poorly differentiated gastric carcinomas with medullary growth pattern, such as acinar type tumors which have a favorable prognosis, and endocrine cell carcinomas and AFP-producing tumors which have poor prognoses and can be considered to be independent clinicopathologic entities. Therefore, the development of new therapeutic tools for such tumors with high malignant potential is required.