Histopathological study of invasive ductal carcinoma (IDC) of the pancreas without associated cancerous occlusion of the main pancreatic duct

BACKGROUND/PURPOSE: [corrected] Invasive ductal carcinoma (IDC) of the pancreas may be associated with cancerous occlusion of the main pancreatic duct (MPD) in its growth process, but at quite low a frequency; there are patients who do not develop this occlusion. METHODS: This study examined the histological features of surgical specimens from 8 patients with IDC without MPD occlusion, in comparison to 32 patients with IDC with this occlusion (controls). The pancreatic duct was identified by confirming the presence of mural elastic fibers on the wall of the pancreatic duct. Immunohistochemical staining was done with Ki-67 antibody. RESULTS: The frequency of IDC without MPD occlusion was very low (5.0% [2/40] patients at Kurume University and 3.1% [4/126] patients at Juntendo University). The number of intraductal carcinoma components was 1.5 +/- 1.1 per specimen in the IDCs without occlusion and 5.9 +/- 2.4 in the controls (P < 0.001). The Ki-67 labeling index was 18.0 +/- 11.7% in the IDCs without occlusion and 30.0 +/- 12.1% in the controls (P < 0.05). The number of intraductal carcinoma components and the Ki-67 labeling index were significantly lower in the IDCs without occlusion than in the controls. CONCLUSIONS: Our findings suggested that these two types of IDC could have different biological features.