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Giant ancient schwannoma of pancreatic head treated by extended pancreatoduodenectomy
Case Report Pancreatology 2004;4:505–508 DOI: 10.1159/000080247
Published online: August 16, 2004
Giant Ancient Schwannoma of Pancreatic Head Treated by Extended Pancreatoduodenectomy Ernst von Dobschuetz a Axel Walch b Martin Werner b Ulrich T. Hopt a Ulrich Adam a a Department
of General and Visceral Surgery and b Institute of Pathology, Albert Ludwigs University, Freiburg, Germany
Key Words Ancient schwannoma W Pancreatectomy W Pancreatoduodenectomy
Abstract We report a case of a 55-year-old woman who was transferred from another center to our university clinic after diagnostic laparotomy with a pancreatic head tumor which was seen to encase the portal vein. Although intraoperative biopsies were performed, a histologic diagnosis of the tumor was not possible before giving suspect to a malignant tumor being resectable only with a vascular resection. In a second operation we performed a pylorus-preserving pancreatoduodenectomy. Due to adhesion of the tumor to the portal vein, a segmental resection and end-to-end anastomosis of the portal vein was necessary. Postoperative histologic diagnosis revealed an ancient schwannoma which was removed in toto being a rare report of this benign tumor in the pancreatic head. Ten months after the operation the patient is without any health problems. Partial resection of the portal vein, which is considered to be a safe procedure in high volume centers, stands in contrary to surgical nihilism of pancreatic head tumors suspecting advanced tumors with vascular involvement. Copyright © 2004 S. Karger AG, Basel and IAP
ABC
© 2004 S. Karger AG, Basel and IAP 1424–3903/04/0046–0505$21.00/0
Fax + 41 61 306 12 34 E-Mail [email protected] www.karger.com
Accessible online at: www.karger.com/pan
Introduction
Surgical resection is the only approach of therapeutic cure in pancreatic head cancer. There is difficulty of definite preoperative diagnosis and consideration of pancreatic head tumors. Due to the bad prognosis of not completely resected malignant tumors, preoperative diagnosis should identify patients with resectable tumors. Next to presence of metastases and local invasion suspect of vascular invasion in preoperative angiography, CT and endoscopic ultrasonography are the most critical criteria of irresectability of pancreatic head tumors. Preoperative confirmation of malignancy by tissue diagnosis is also a wish of the operating surgeon which is very difficult to fulfill.
Case Report A 55-year-old obese woman was transferred from another hospital center to the university department. The patient complained about 2 months of perianal bleeding without weight loss and a leftsided ischialgia. All laboratory data including CA 19-9 were normal except the lipase of 225 U/l. A physical examination showed discrete tenderness in the left and right lower abdomen and a hemorrhoidal prolapse which was resected preoperatively by an ambulant procedure. Abdominal sonography revealed a tumor in the right abdomen being highly susceptible to be related to the pancreatic head. Therefore a CT scan was performed revealing a 8 ! 5 ! 7 cm measuring
Ernst von Dobschuetz, MD Department of General and Visceral Surgery University of Freiburg, Hugstetter Strasse 55 DE–79110 Freiburg (Germany) Tel. +49 761 2702401, Fax +49 721 151319696, E-Mail [email protected]
Fig. 2. Mesentericography with splenoportogram showing a bilateral encasement (arrow) of the portal vein close to the confluens.
Fig. 1. Preoperative CT scan revealing an 8 ! 5 ! 7 cm measuring tumor in the pancreatic head and corpus with possible infiltration of the left liver lobe and encasement of the common hepatic artery (a, arrow); suspected encasement of the portal vein (b, arrow).
tumor in the pancreatic head and corpus being adjacent to the gastric curvature and left liver lobe (fig. 1). The aspect of the tumor was cystic but a neoplasm was also susceptible. A preoperative Gastrographin passage and an ERCP gave no suspect of infiltrative growth. In a mesentericography, a bilateral encasement of the portal vein close to the confluens of splenic and superior mesenteric vein was shown (fig. 2). Due to the absence of metastases, a laparotomy was performed with the intention of curative resection. During this operation the tumor was adjacent to the pancreatic head with massive circular involvement of the hepatic artery. Intraoperative biopsies gave no definitive diagnosis with a high suspicion of a malignant tumor. Since the portal vein showed a complete encasement it was decided to finish the operation as an explorative laparotomy and refer the patient to our university center. Three days later the patient was operated on in our surgical center. After laparotomy the common hepatic artery and the upper mesenteric vein could be completely
506
Pancreatology 2004;4:505–508
freed from the tumor. Due to adherence to the portal vein, 4 cm of vessel were resected and an end-to-end anastomosis was performed. After closure of the portal vein the operation was finished as a pylorus-preserving pancreatic head resection as described elsewhere [1]. Postoperatively the patient recovered slowly. She presented recurrent pleural effusions which required multiple drainages and a urinary infection with Enterococcus which was treated by antibiotics. Seven days after the operation she developed a clinically asymptomatic leakage from the pancreaticojejunostomy with amylase values in the intraoperatively inserted drain next to the anastomosis of 1 8,000 U/l. This leakage stopped spontaneously. The patient could be discharged after 1 month without any clinical problem. Ten months later the patient is fine without any health problems. Gross Findings The pancreatoduodenectomy specimen present in the head of the pancreas was a tumor with 6 cm in the greatest diameter. Sectioning of the specimen showed a well-demarcated and capsulated tumor mass which was almost completely located within the pancreatic parenchyma without reference to retroperitoneal structures. The cut surface was lobulated and patchy yellow with extensive hemorrhage and cystic degeneration. The capsule of the tumor was adhesive to a segment of the portal vein. Microscopic Findings Extensive areas with stromal degenerative changes, including organization of remote hemorrhage and widespread hyalinization, were seen. The peripheral portion was composed of palisading sheets of spindle cells, focally appearing as minute fragments of Antoni A tissue pattern. Foam cells with xanthic changes and chronic inflam-
von Dobschuetz/Walch/Werner/Hopt/ Adam
mation were common (fig. 3). Advanced degenerative nuclear changes characterized by marked pleomorphism, hyperchromasia and cytoplasmatic pseudoinclusion formation was present. Immunostains of the peripheral portion showed strong positivity for S-100 (fig. 4) and vimentin, but negativity staining for keratin, CD34, CD117, desmin and ·-actin. Microscopic sections demonstrated that the tumor was defined to the pancreas (fig. 5). The tumor was capsuled by a thick fibrocollagenous layer. The portal vein was compressed by the tumor but showed no tumor infiltration.
Discussion
The low rate of 5-year survivors in patients resected due to pancreatic cancer has led to a nihilistic position in the treatment of pancreatic cancer [2]. The immense improvement in surgical technique has lowered perioperative morbidity and mortality below 5% in high volume centers [3]. In high volume centers morbidity and mortality of patients with vessel resection as compared to patients without resection of the portal or mesenteric vein have no significant outcome difference [4]. Since in our case histology was not certain and a malignancy was suspected, portal vein resection was the only way of performing an intended curative resection in this patient. Preoperative diagnosis of vascular involvement by mesentericography gives only an idea of resectability [5]. In many gastrointestinal tumors, preoperative histologic diagnosis is important. However, preoperative histomorphological diagnosis on small biopsy samples of the pancreas may be difficult in some instances. Especially those patients who have very small tumors profit most from the prompt resection of the tumor. A negative result of the biopsy for us is no proof that the tumor is not malignant and there is concern that biopsy of the tumor will hasten its dissemination. Earnhardt et al. [6] calculated a negative predictive value of preoperative fine-needle histology of only 74% and even intraoperatively during explorative laparotomy they could show a false negative rate of 5–10%. In our case the histologic diagnosis during explorative laparotomy was hampered, since merely peritumoral tissue was represented in the biopsy due to sampling error. Chronic pancreatitis and other benign tumors as in this case are also adequately treated with pancreatoduodenec-
3
4
Fig. 3. Schwannoma with degenerative changes such as foam cells with xanthic changes. HE. !200. Fig. 4. The immunoprofile of the tumor includes strong S-100 immunoreactivity. HE. !200. Fig. 5. Low-power view showing the tumor mass (T) which is encapsulated (C) and localized within the pancreatic tissue (P). HE. !25.
Ancient Schwannoma
5
Pancreatology 2004;4:505–508
507
tomy. Thus, in our opinion, a biopsy is only needed when no operation is possible or the patient is considered to get neoadjuvant treatment. The healing process after this explorative laparotomy could make the possibility of a pancreatic head resection technically difficult or impossible after a certain time due to adhesion formation and scars. Therefore, we decided to perform this resection within 3 days after the explorative laparotomy without waiting for a definitive histologically proven diagnosis after immunohistologic staining. Technical operability was another important fact against having a definitive histologic diagnosis in this special case. Mesenchymal tumors account for 1–2% of all pancreatic tumors and are classified according to their histologic origin [7]. Schwannomas are very rare lesions arising from the Schwann cells enveloping the sympathetic and parasympathetic nervous fibers. According to das Gupta [8], the most common location of this tumor is the head and neck region. Schwannomas are morphologically well characterized. This type of neoplasm usually consists of a cellular component (Antoni type A area) and a loose hypocellular component (Antoni type B). The cases of schwannoma displaying pronounced degenerative changes with cyst formation, calcification, hemorrhage, hyalinization and xanthomatous infiltration as demonstrated in the described case here are called ancient schwannoma [9]. Degenerative nuclear atypia is also another peculiar finding. In cases of high prevalence of Antoni type B tissue, the loose architecture with regression zones mostly due to vascular thrombosis give a pseudocystic appearance in the CT scan with the differential diagnosis of epithelial tumors (microcystic serous adenoma, solid and papillary
neoplasm and mucinous macrocystic tumor) [10]. Therefore, preoperative images can only give the suspect of the entity of the pancreatic head tumor. Reports on this tumor entity in pancreas are very rare [for reviews, see 11–13]. The pathohistological differential diagnosis comprises primary non-epithelial tumors such as benign or malignant soft tissue tumors, as well as malignant lymphoma. Furthermore, secondary tumors should be recognized. Relatively few extrapancreatic neoplasms may also involve the pancreas. Among these are primary schwannomas of the retroperitoneum. However, the case presented here demonstrated a well-demarcated and capsulated tumor mass which was almost completely located within the pancreatic parenchyma without reference to retroperitoneal structures. Thus, a schwannoma of the retroperitoneum is unlikely. Only a few cases mostly in the body and tail are reported in the literature. Normally, schwannomas of the pancreas are !5 cm. Malignant transformation of a benign schwannoma is exceedingly rare. The few cases of reported malignant schwannomas are mostly associated with von Recklinghausen’s disease and therefore thought to be misdiagnosed neurofibromas [11]. In summary, definitive histologic diagnosis of pancreatic head tumors except in patients with planed neoadjuvant therapy should, whenever possible, only be established by surgery. Preoperative encasement of the mesenterico-portal-venous axis is no contraindication of pancreatic head resection. This case of a giant pancreatic head tumor of extraordinary histology is a good example against therapeutic nihilism and for individual decisionmaking of the operating surgeon giving consideration to the preoperative findings.
References 1 Riediger H, Makowiec F, Schareck WD, Hopt UT, Adam U: Delayed gastric emptying after pylorus-preserving pancreatoduodenectomy is strongly related to other postoperative complications. J Gastrointest Surg 2003;7:758–765. 2 Gudjonsson B: Cancer of the pancreas. Fifty years of surgery. Cancer 1987;60:2284–2303. 3 Trede M, Schwall G, Saeger HD: Survival after pancreatoduodenectomy. 118 consecutive resections without an operative mortality. Ann Surg 1990;211:447–458. 4 Harrison LE, Klimstra DS, Brennan MF: Isolated portal vein involvement in pancreatic adenocarcinoma. A contraindication for resection? Ann Surg 1996;224:342–347. 5 Murugiah M, Windsor JA, Redhead DN, O’Neill JS, Suc B, Garden OJ, Carter DC: The role of selective visceral angiography in the management of pancreatic and periampullary cancer. World J Surg 1993;17:796–800.
508
6 Earnhardt RC, McQuone SJ, Minasi JS, Feldman PS, Jones RS, Hanks JB: Intraoperative fine needle aspiration of pancreatic and extrahepatic biliary masses. Surg Gynecol Obstet 1993;177:147–152. 7 Kloppel G, Maillet B: Classification and staging of pancreatic nonendocrine tumors. Radiol Clin North Am 1989;27:105–119. 8 Das Gupta TK: Tumors of the peripheral nerves; in Das Gupta (ed): Tumor of the soft tissue. Norwalk, Appleton-Century-Crofts, 1983, pp 494–551. 9 Lee JS, Kim HS, Jung JJ, Han SW, Kim YB: Ancient schwannoma of the pancreas mimicking a cystic tumor. Virchows Arch 2001;439: 697–699.
Pancreatology 2004;4:505–508
10 Ferrozzi F, Zuccoli G, Bova D, Calculli L: Mesenchymal tumors of the pancreas: CT findings. J Comput Assist Tomogr 2000;24:622–627. 11 Feldman L, Philpotts LE, Reinhold C, Duguid WP, Rosenberg L: Pancreatic schwannoma: Report of two cases and review of the literature. Pancreas 1997;15:99–105. 12 Brown SZ, Owen DA, O’Connell JX, Scudamore CH: Schwannoma of the pancreas: A report of two cases and a review of the literature. Mod Pathol 1998;11:1178–1182. 13 Hsiao WC, Lin PW, Chang KC: Benign retroperitoneal schwannoma mimicking a pancreatic cystic tumor: Case report and literature review. Hepatogastroenterology 1998;45:2418– 2420.
von Dobschuetz/Walch/Werner/Hopt/ Adam
Published online: August 16, 2004
Giant Ancient Schwannoma of Pancreatic Head Treated by Extended Pancreatoduodenectomy Ernst von Dobschuetz a Axel Walch b Martin Werner b Ulrich T. Hopt a Ulrich Adam a a Department
of General and Visceral Surgery and b Institute of Pathology, Albert Ludwigs University, Freiburg, Germany
Key Words Ancient schwannoma W Pancreatectomy W Pancreatoduodenectomy
Abstract We report a case of a 55-year-old woman who was transferred from another center to our university clinic after diagnostic laparotomy with a pancreatic head tumor which was seen to encase the portal vein. Although intraoperative biopsies were performed, a histologic diagnosis of the tumor was not possible before giving suspect to a malignant tumor being resectable only with a vascular resection. In a second operation we performed a pylorus-preserving pancreatoduodenectomy. Due to adhesion of the tumor to the portal vein, a segmental resection and end-to-end anastomosis of the portal vein was necessary. Postoperative histologic diagnosis revealed an ancient schwannoma which was removed in toto being a rare report of this benign tumor in the pancreatic head. Ten months after the operation the patient is without any health problems. Partial resection of the portal vein, which is considered to be a safe procedure in high volume centers, stands in contrary to surgical nihilism of pancreatic head tumors suspecting advanced tumors with vascular involvement. Copyright © 2004 S. Karger AG, Basel and IAP
ABC
© 2004 S. Karger AG, Basel and IAP 1424–3903/04/0046–0505$21.00/0
Fax + 41 61 306 12 34 E-Mail [email protected] www.karger.com
Accessible online at: www.karger.com/pan
Introduction
Surgical resection is the only approach of therapeutic cure in pancreatic head cancer. There is difficulty of definite preoperative diagnosis and consideration of pancreatic head tumors. Due to the bad prognosis of not completely resected malignant tumors, preoperative diagnosis should identify patients with resectable tumors. Next to presence of metastases and local invasion suspect of vascular invasion in preoperative angiography, CT and endoscopic ultrasonography are the most critical criteria of irresectability of pancreatic head tumors. Preoperative confirmation of malignancy by tissue diagnosis is also a wish of the operating surgeon which is very difficult to fulfill.
Case Report A 55-year-old obese woman was transferred from another hospital center to the university department. The patient complained about 2 months of perianal bleeding without weight loss and a leftsided ischialgia. All laboratory data including CA 19-9 were normal except the lipase of 225 U/l. A physical examination showed discrete tenderness in the left and right lower abdomen and a hemorrhoidal prolapse which was resected preoperatively by an ambulant procedure. Abdominal sonography revealed a tumor in the right abdomen being highly susceptible to be related to the pancreatic head. Therefore a CT scan was performed revealing a 8 ! 5 ! 7 cm measuring
Ernst von Dobschuetz, MD Department of General and Visceral Surgery University of Freiburg, Hugstetter Strasse 55 DE–79110 Freiburg (Germany) Tel. +49 761 2702401, Fax +49 721 151319696, E-Mail [email protected]
Fig. 2. Mesentericography with splenoportogram showing a bilateral encasement (arrow) of the portal vein close to the confluens.
Fig. 1. Preoperative CT scan revealing an 8 ! 5 ! 7 cm measuring tumor in the pancreatic head and corpus with possible infiltration of the left liver lobe and encasement of the common hepatic artery (a, arrow); suspected encasement of the portal vein (b, arrow).
tumor in the pancreatic head and corpus being adjacent to the gastric curvature and left liver lobe (fig. 1). The aspect of the tumor was cystic but a neoplasm was also susceptible. A preoperative Gastrographin passage and an ERCP gave no suspect of infiltrative growth. In a mesentericography, a bilateral encasement of the portal vein close to the confluens of splenic and superior mesenteric vein was shown (fig. 2). Due to the absence of metastases, a laparotomy was performed with the intention of curative resection. During this operation the tumor was adjacent to the pancreatic head with massive circular involvement of the hepatic artery. Intraoperative biopsies gave no definitive diagnosis with a high suspicion of a malignant tumor. Since the portal vein showed a complete encasement it was decided to finish the operation as an explorative laparotomy and refer the patient to our university center. Three days later the patient was operated on in our surgical center. After laparotomy the common hepatic artery and the upper mesenteric vein could be completely
506
Pancreatology 2004;4:505–508
freed from the tumor. Due to adherence to the portal vein, 4 cm of vessel were resected and an end-to-end anastomosis was performed. After closure of the portal vein the operation was finished as a pylorus-preserving pancreatic head resection as described elsewhere [1]. Postoperatively the patient recovered slowly. She presented recurrent pleural effusions which required multiple drainages and a urinary infection with Enterococcus which was treated by antibiotics. Seven days after the operation she developed a clinically asymptomatic leakage from the pancreaticojejunostomy with amylase values in the intraoperatively inserted drain next to the anastomosis of 1 8,000 U/l. This leakage stopped spontaneously. The patient could be discharged after 1 month without any clinical problem. Ten months later the patient is fine without any health problems. Gross Findings The pancreatoduodenectomy specimen present in the head of the pancreas was a tumor with 6 cm in the greatest diameter. Sectioning of the specimen showed a well-demarcated and capsulated tumor mass which was almost completely located within the pancreatic parenchyma without reference to retroperitoneal structures. The cut surface was lobulated and patchy yellow with extensive hemorrhage and cystic degeneration. The capsule of the tumor was adhesive to a segment of the portal vein. Microscopic Findings Extensive areas with stromal degenerative changes, including organization of remote hemorrhage and widespread hyalinization, were seen. The peripheral portion was composed of palisading sheets of spindle cells, focally appearing as minute fragments of Antoni A tissue pattern. Foam cells with xanthic changes and chronic inflam-
von Dobschuetz/Walch/Werner/Hopt/ Adam
mation were common (fig. 3). Advanced degenerative nuclear changes characterized by marked pleomorphism, hyperchromasia and cytoplasmatic pseudoinclusion formation was present. Immunostains of the peripheral portion showed strong positivity for S-100 (fig. 4) and vimentin, but negativity staining for keratin, CD34, CD117, desmin and ·-actin. Microscopic sections demonstrated that the tumor was defined to the pancreas (fig. 5). The tumor was capsuled by a thick fibrocollagenous layer. The portal vein was compressed by the tumor but showed no tumor infiltration.
Discussion
The low rate of 5-year survivors in patients resected due to pancreatic cancer has led to a nihilistic position in the treatment of pancreatic cancer [2]. The immense improvement in surgical technique has lowered perioperative morbidity and mortality below 5% in high volume centers [3]. In high volume centers morbidity and mortality of patients with vessel resection as compared to patients without resection of the portal or mesenteric vein have no significant outcome difference [4]. Since in our case histology was not certain and a malignancy was suspected, portal vein resection was the only way of performing an intended curative resection in this patient. Preoperative diagnosis of vascular involvement by mesentericography gives only an idea of resectability [5]. In many gastrointestinal tumors, preoperative histologic diagnosis is important. However, preoperative histomorphological diagnosis on small biopsy samples of the pancreas may be difficult in some instances. Especially those patients who have very small tumors profit most from the prompt resection of the tumor. A negative result of the biopsy for us is no proof that the tumor is not malignant and there is concern that biopsy of the tumor will hasten its dissemination. Earnhardt et al. [6] calculated a negative predictive value of preoperative fine-needle histology of only 74% and even intraoperatively during explorative laparotomy they could show a false negative rate of 5–10%. In our case the histologic diagnosis during explorative laparotomy was hampered, since merely peritumoral tissue was represented in the biopsy due to sampling error. Chronic pancreatitis and other benign tumors as in this case are also adequately treated with pancreatoduodenec-
3
4
Fig. 3. Schwannoma with degenerative changes such as foam cells with xanthic changes. HE. !200. Fig. 4. The immunoprofile of the tumor includes strong S-100 immunoreactivity. HE. !200. Fig. 5. Low-power view showing the tumor mass (T) which is encapsulated (C) and localized within the pancreatic tissue (P). HE. !25.
Ancient Schwannoma
5
Pancreatology 2004;4:505–508
507
tomy. Thus, in our opinion, a biopsy is only needed when no operation is possible or the patient is considered to get neoadjuvant treatment. The healing process after this explorative laparotomy could make the possibility of a pancreatic head resection technically difficult or impossible after a certain time due to adhesion formation and scars. Therefore, we decided to perform this resection within 3 days after the explorative laparotomy without waiting for a definitive histologically proven diagnosis after immunohistologic staining. Technical operability was another important fact against having a definitive histologic diagnosis in this special case. Mesenchymal tumors account for 1–2% of all pancreatic tumors and are classified according to their histologic origin [7]. Schwannomas are very rare lesions arising from the Schwann cells enveloping the sympathetic and parasympathetic nervous fibers. According to das Gupta [8], the most common location of this tumor is the head and neck region. Schwannomas are morphologically well characterized. This type of neoplasm usually consists of a cellular component (Antoni type A area) and a loose hypocellular component (Antoni type B). The cases of schwannoma displaying pronounced degenerative changes with cyst formation, calcification, hemorrhage, hyalinization and xanthomatous infiltration as demonstrated in the described case here are called ancient schwannoma [9]. Degenerative nuclear atypia is also another peculiar finding. In cases of high prevalence of Antoni type B tissue, the loose architecture with regression zones mostly due to vascular thrombosis give a pseudocystic appearance in the CT scan with the differential diagnosis of epithelial tumors (microcystic serous adenoma, solid and papillary
neoplasm and mucinous macrocystic tumor) [10]. Therefore, preoperative images can only give the suspect of the entity of the pancreatic head tumor. Reports on this tumor entity in pancreas are very rare [for reviews, see 11–13]. The pathohistological differential diagnosis comprises primary non-epithelial tumors such as benign or malignant soft tissue tumors, as well as malignant lymphoma. Furthermore, secondary tumors should be recognized. Relatively few extrapancreatic neoplasms may also involve the pancreas. Among these are primary schwannomas of the retroperitoneum. However, the case presented here demonstrated a well-demarcated and capsulated tumor mass which was almost completely located within the pancreatic parenchyma without reference to retroperitoneal structures. Thus, a schwannoma of the retroperitoneum is unlikely. Only a few cases mostly in the body and tail are reported in the literature. Normally, schwannomas of the pancreas are !5 cm. Malignant transformation of a benign schwannoma is exceedingly rare. The few cases of reported malignant schwannomas are mostly associated with von Recklinghausen’s disease and therefore thought to be misdiagnosed neurofibromas [11]. In summary, definitive histologic diagnosis of pancreatic head tumors except in patients with planed neoadjuvant therapy should, whenever possible, only be established by surgery. Preoperative encasement of the mesenterico-portal-venous axis is no contraindication of pancreatic head resection. This case of a giant pancreatic head tumor of extraordinary histology is a good example against therapeutic nihilism and for individual decisionmaking of the operating surgeon giving consideration to the preoperative findings.
References 1 Riediger H, Makowiec F, Schareck WD, Hopt UT, Adam U: Delayed gastric emptying after pylorus-preserving pancreatoduodenectomy is strongly related to other postoperative complications. J Gastrointest Surg 2003;7:758–765. 2 Gudjonsson B: Cancer of the pancreas. Fifty years of surgery. Cancer 1987;60:2284–2303. 3 Trede M, Schwall G, Saeger HD: Survival after pancreatoduodenectomy. 118 consecutive resections without an operative mortality. Ann Surg 1990;211:447–458. 4 Harrison LE, Klimstra DS, Brennan MF: Isolated portal vein involvement in pancreatic adenocarcinoma. A contraindication for resection? Ann Surg 1996;224:342–347. 5 Murugiah M, Windsor JA, Redhead DN, O’Neill JS, Suc B, Garden OJ, Carter DC: The role of selective visceral angiography in the management of pancreatic and periampullary cancer. World J Surg 1993;17:796–800.
508
6 Earnhardt RC, McQuone SJ, Minasi JS, Feldman PS, Jones RS, Hanks JB: Intraoperative fine needle aspiration of pancreatic and extrahepatic biliary masses. Surg Gynecol Obstet 1993;177:147–152. 7 Kloppel G, Maillet B: Classification and staging of pancreatic nonendocrine tumors. Radiol Clin North Am 1989;27:105–119. 8 Das Gupta TK: Tumors of the peripheral nerves; in Das Gupta (ed): Tumor of the soft tissue. Norwalk, Appleton-Century-Crofts, 1983, pp 494–551. 9 Lee JS, Kim HS, Jung JJ, Han SW, Kim YB: Ancient schwannoma of the pancreas mimicking a cystic tumor. Virchows Arch 2001;439: 697–699.
Pancreatology 2004;4:505–508
10 Ferrozzi F, Zuccoli G, Bova D, Calculli L: Mesenchymal tumors of the pancreas: CT findings. J Comput Assist Tomogr 2000;24:622–627. 11 Feldman L, Philpotts LE, Reinhold C, Duguid WP, Rosenberg L: Pancreatic schwannoma: Report of two cases and review of the literature. Pancreas 1997;15:99–105. 12 Brown SZ, Owen DA, O’Connell JX, Scudamore CH: Schwannoma of the pancreas: A report of two cases and a review of the literature. Mod Pathol 1998;11:1178–1182. 13 Hsiao WC, Lin PW, Chang KC: Benign retroperitoneal schwannoma mimicking a pancreatic cystic tumor: Case report and literature review. Hepatogastroenterology 1998;45:2418– 2420.
von Dobschuetz/Walch/Werner/Hopt/ Adam