Invasive growth patterns of hepatic hilar ductal carcinoma. A histologic analysis of 18 surgical cases

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Abstract
Background. Postoperative recurrence of hepatic hilar ductal carcinoma usually occurs in a localized region around the surgical margin, such as the bile duct. This study was aimed at assessing the invasive patterns of the hepatic hilar ductal carcinoma by histologically examining surgical specimens obtained by extended liver resection, especially the involvement of intrahepatic duct. Methods. Eighteen resected specimens of hepatic hilar ductal carcinoma were histologically investigated. Multiple sections vertical to the extrahepatic and intrahepatic bile duct were made at a 5‐mm interval. The extension of carcinoma was evaluated on each of three layers (mucosal, extramucosal‐intramural, and extramural), and routes of the invasion were examined. Results. Extramucosal extent toward the hepatic side was observed in 14 patients (77.8%) and that toward the duodenal side in 8 patients (44.4%) (P ≤ 0.05). The distance of extramucosal tumor extent was also significantly longer (P ≤ 0.05) in the hepatic side than in the duodenal side. Histologic tumor margin was usually identified in the extramural layer. Two patients had discontinuous extramucosal invasion. The lymphatic invasions were observed most frequently, followed by perineural invasion, and venous invasion was rare. In the extramucosal invasion of the liver, the left dominant carcinomas had extended toward the left, whereas those right dominant had extended toward the right (P ≤ 0.05). Well differentiated tubular adenocarcinomas extended to the liver more extensively than moderately and poorly differentiated ones, but not significantly. Conclusions. The authors examined the extramucosal invasion of hepatic hilar ductal carcinoma. This invasion extended more frequently and further to the hepatic side than to the duodenal side, usually by the route of the extramural layer. Cancer 1994; 73:2922–9.