The value of the preoperative mucosal biopsy in the diagnosis of colorectal mucinous adenocarcinoma.

Abstract

As a rule, mucinous colorectal adenocarcinomas tend to be at a more advanced stage at the time of discovery than their nonmucinous counterparts. This study assesses the potential value of the preoperative biopsy in the diagnosis of such mucinous adenocarcinomas. The preoperative biopsy specimens and the corresponding resection specimens of 189 patients with colorectal carcinomas were examined and compared by conventional light microscopic study. The stage of the tumor, using the modified Dukes classification of Astler and Coller, was correlated with the percentage of mucinous component (MC) in the resection specimens. The MC in the preoperative biopsy was assessed by the presence of: (1) malignant-appearing glands disrupted by the presence of abundant extruded intraluminal mucin; (2) pools of mucin in the connective stroma of the adenocarcinoma; and (3) superficial pools of mucin containing ribbons or clusters of neoplastic epithelial cells. The presence of a significant (more than 25%) MC in the resection specimen correlated well with an advanced stage of the tumor; 82% of tumors with more than 25% MC were at the B2 or higher stage, compared with 64% of tumors with less than 25% MC (P < 0.05). Finding MC in the preoperative biopsy correlated well with a similar finding in the resection specimen and with a B2 or higher stage of the tumor in such specimens; 83% of MC-positive biopsy specimens exhibited more than 25% MC in the corresponding resection specimen, whereas only 10% of MC-negative biopsy specimens were associated with a surgical specimen containing more than 25% MC (P < 0.001). Similarly, 83% of such MC-positive biopsy specimens revealed a carcinoma at the B2 or higher stage upon resection, compared with 63% of the MC-negative biopsy specimens (P < 0.02). Colorectal adenocarcinomas showing MC in the preoperative biopsy are significantly more likely to reveal a high mucin content and to be at an advanced stage at resection. Thus, such preoperative findings should be recorded and made available on a prospective basis to the treating physicians.