Two types of lymphatic invasion in lymph node metastasis with special references to the morphology of gastric carcinomas and immunohistology of e-cadherin and -catenin.

Two types of lymphatic invasion were distinguishable in lymph nodes (LN) with metastasis of a gastric carcinoma (GC). One was an embolic (E) type of lymphatic invasion that was characterized with embolus of carcinoma cells in collecting lymphatics. Infiltration of carcinomas as single cells or as tiny clusters through lymphatic capillaries were features of the other infiltrative (I) type of lymphatic invasion and were found in the interstitial spaces of peri-lymphnodal fat tissues. The latter was an early event during metastasis, even when not yet apparent in LN. Both types of lymphatic invasion coexisted, not infrequently, in advanced stages, but pure I type occurred exclusively in diffuse type GC ( 2< 0.005) C regardless of the existence of metastasis in LN. E type was more frequently encountered solely or predominantly in intestinal type GC ( 2< 0.05). Of the destructive lesions of collecting lymphatics, fibrous occlusion or stenosis and large emboli were seen in intestinal type GC ( 2< 0.005). Early I type lesions were more seen in diffuse type GC ( 2< 0.005). The incidence of destruction of collecting lymphatics by carcinoma cells from outside and the existence of single cells in collecting lymphatics were seen more in diffuse type GC, but not significantly. Immunohistology revealed that E-cadherin (Ec) and -catenin( c) were expressed positively in cytoplasm of carcinoma cells of diffuse GC at 50.0% and 78.5%, respectively. However, c of carcinoma cells exhibiting I type of lymphatic invasion were expressed negatively or much less. The mechanism of I type of lymphatic invasion, its low expression of c, and the heterogeneity of GC were discussed. It is necessary to clarify the I type of lymphatic invasion to gain improvements in curability.