Pancreas head carcinoma: frequency of invasion to soft tissue adherent to the superior mesenteric artery.

Despite radical extension of surgical procedures, the cure rate of pancreatic head carcinoma patients still remains low. A cause of this concerns unsuccessful locoregional control, which may originate from a positive surgical margin near the superior mesenteric artery (SMA). However, no studies have examined invasion of pancreatic carcinoma around the SMA. En bloc resection of the head of the pancreas and the superior mesenteric vessels was performed on 6 patients who had pancreatic head carcinoma invading the superior mesenteric vein. The specimens were cut perpendicular to the SMA and consecutive serial sections were made. The slices were stained with hematoxylin and eosin or immunohistochemistry for cytokeratin 19 to easily detect carcinoma tissue under a microscope. Nodal metastasis around the SMAs was found in all of the cases. There were no characteristics of the arrangement of the metastatic nodes along the SMA. Lymphatic emboli were often observed close to the metastatic nodes. Neural invasions were detected around the tumors in every case and were continuously connected with the extrapancreatic nerve plexus. The nerve plexus covering the SMA were involved in 4 cases. Involvement was observed mainly behind the SMA, reaching as far as the left side of the SMA in 3 cases. The invasion extended further upwards along the right side of SMA for the celiac nerve plexus. The lymphatics and the nerve plexus in the area around the SMA were frequently involved by pancreatic head carcinoma. This involvement would have been left behind unless the SMA was resected.