[Histological differentiation of Rokitansky-Aschoff sinus involvement from stromal invasion of carcinoma of the gallbladder].

It is often difficult to judge the depth of invasion in carcinomas of the gallbladder, because some extend along Rokitansky-Aschoff sinus (RAS) without stromal invasion. The purpose of this study is to clarify the histological differentiation of RAS involvement from stromal invasion. One hundred and fifty three RAS, which were in 31 gallbladders without carcinoma, were examined histologically. They were surrounded by "peri-RAS stroma", which was similar to lamina propria mucosae. Cancerous glands, which were surrounded by "peri-RAS stroma" or showed "border (front)" of cancerous and non-cancerous epithelia, were judged to suggest RAS involvement of carcinoma. Desmoplastic stroma surrounding invasive carcinoma could be histologically distinguished from "peri-RAS stroma". Therefore it was possible to differentiate RAS involvement from stromal invasion. In 13 carcinomas which reached subserosal layer by way of RAS involvement, there was none of vascular permeation, perineural invasion and lymph node metastasis. No recurrence was encountered among these patients. Therefore these carcinomas, together with carcinomas confined to mucosa or proper muscle layer, can be entitled "early carcinoma of the gallbladder".