Periportal Schwannoma: Two Case Reports and Review of Periportal Mass

                          http://austinpublishinggroup.com/gastrointestinal-cancer/currentissue.php

Schwannomas arebenign tumors that arise from Schwann cells of peripheral nerve myelin sheaths. Initially reported in 1988 by Daimaru et al. Gastrointestinal schwannomas have an excellent prognosis after surgical resection. Patients with periportal schwannomas can present with abdominal pain or concerning features such as weight loss, jaundice or anorexia raising suspicion for a malignant tumor. Schwannomas characteristically undergo cystic degeneration due to vascular thrombosis and subsequent necrosis. Computed Tomography (CT) scan shows a well-defined, hypodense, heterogeneous mass with peripheral enhancement making the differentiation from a malignant tumor even more difficult. Only 15 cases of periportal schwannomas have been described in the literature, and preoperative diagnoses could not be made in any of them. All of these patients underwent open surgical resection.

We present two cases of periportal schwannomas approached laparoscopically. The first patient underwent laparoscopic resection of a periportal schwannoma arising from the proper hepatic artery. To our knowledge, this is the first reported case of laparoscopic resection of periportal schwannoma. The second patient underwent a diagnostic laparoscopy, and the periportal mass was confirmed as a benign schwannoma by intraoperative frozen section. The tumor was encased around the extrahepatic biliary tree, so it was left in-situ to avoid unnecessary extensive biliary surgery. 55-year-old Caucasian female presented with six months of severe abdominal pain, early satiety, bloating, steatorrhea and a fifteen-pound weight loss. Past surgical history was significant for laparoscopic cholecystectomy. Her laboratory studies (complete blood count, liver function test) and tumor markers including Carcino Embryonic Antigen (CEA) and Cancer Antigen 19-9 (CA 19-9) were within normal limit. Both upper and lower endoscopies were normal. Abdominal CT showed a 5cm well-defined hypodense mass in the porta hepatis (Figure 1a). No enlarged hilar lymph nodes were identified. This was confirmed on an MRI as a 5cm complex, septated cystic mass, hyperintense on T2 signal, adjacent to porta hepatis but separate from the pancreas and biliary tree.

 There was no intra or extra-hepatic bile duct dilatation. A decision was made to pursue laparoscopic resection of the periportal mass based on the extent to which the symptoms affected the patient’s quality of life. Intraperitoneal access was gained through a Hasson cannula and abdomen was insufflated with CO₂ pneumoperitoneum to a pressure of 12mmHg. Four 5-mm trocars were placed in the upper abdomen. After introduction of the laparoscope (KARL STORZ, Tuttlingen, Germany), the mass was easily identified posterior to the hepatic artery. It was dissected carefully from surrounding structures using an ultrasonic dissector (SonoSurg, Olympus, Tokyo, Japan). A network of peripheral nerves was seen to be entering the tumor. The mass appeared to arise from the proper hepatic artery. The cystic duct stump from prior cholecystectomy was identified by the presence of surgical clips . An intraoperative cholangiogram (IOC) through the cystic duct demonstrated normal filling of the bile duct and no communication with the periportal mass.