Solitary malignant schwannoma of the pancreas: report of a case and ultrastructural examination

Pancreatic schwannoma: Case report, clinico-pathologic correlation, and review of the literature

Schwannomas are common peripheral nerve sheath tumors that typically occur on the head, neck, trunk, or extremities. Intra-abdominal schwannomas, however, are rare. We describe a young woman who presented for imaging evaluation of suspected nephrolithiasis and was incidentally found to have a schwannoma centered within the pancreatic parenchyma. In addition, we detail the clinical, imaging, and histopathologic features of pancreatic schwannoma and summarize diagnosis and management of this rare clinical entity.

Successful treatment of pancreatic schwannoma by enucleation: A case report

RATIONALE

Pancreatic schwannomas are extremely rare and are difficult to diagnose preoperatively. Over the past 50 years, only 96 cases of pancreatic schwannoma have been reported in English literature. Herein, we report a case of pancreatic schwannoma treated with enucleation.

PATIENT CONCERNS

A 66-year-old woman visited a local hospital due to ventosities. Ultrasonography and computed tomography revealed a pancreatic mass. She visited our hospital for further diagnosis and treatment.

DIAGNOSIS AND INTERVENTIONS

Magnetic resonance imaging revealed a tumor in the pancreatic body, and a solid pseudopapillary tumor was considered preoperatively. During the surgery, a pancreatic mass was found growing in the pancreatic body and tail. A successful tumor enucleation was performed. The mass was 7 × 6 × 3 cm in size with a thin capsule. Pathological examination revealed that the tumor was mainly composed of spindle-shaped cells with a palisading arrangement and no atypia. Both hypercellular and hypocellular areas were visible. Immunohistochemical staining showed that protein S-100 was strongly positive. The tumor was diagnosed as a benign schwannoma originating from the pancreatic body and tail.

OUTCOMES

Postoperatively, the patient showed good recovery. During the 24-month follow-up period, the patient remained well and free of complications.

LESSONS

Pancreatic schwannomas are extremely rare and difficult to diagnose using imaging examinations. Enucleation is a safe and efficacious treatment for exophytic pancreatic schwannomas.

Pancreatic Nerve Sheath Tumors: a Single Institutional Series and Systematic Review of the Literature

INTRODUCTION

Improvement in imaging has resulted in frequent diagnosis of benign and premalignant pancreatic tumors. Pancreatic nerve sheath (PNS) tumors are one of the rarest pancreatic tumors. Literature on PNS is limited and their biology is poorly understood. Here, we report the largest series of PNS tumors to date and review the literature to evaluate the current data available on PNS tumors.

METHODS

An institutional database was used to identify patients who underwent resection for PNS tumors. Clinicopathological characteristics and outcomes of these patients were reported. Furthermore, a review of literature was performed.

RESULTS

From January 1994 through December 2016, seven patients underwent resection for PNS tumors. The median age was 57.7 years (IQR, 44.9-61.9) and the sex was approximately equally distributed (male = 4; 57.1%). Three (42.9%) patients were diagnosed incidentally and six (85.7%) were misdiagnosed as having other pancreatic tumors. The median tumor size was 2.1 (IQR 1.8-3.0) cm and six (85.7%) had no nodal disease. At a median follow-up of 15.5 (IQR 13.7-49.3) months, six patients were alive without evidence of disease and one patient was lost to follow-up. The literature review identified 49 studies reporting 54 patients with PNS tumors. Forty-six were misdiagnosed as having other pancreatic tumors. The median tumor size was 3.6 (range 1-20) cm, nodal disease was present in six patients (22.2%), and no patient had distant metastatic disease. At the time of last follow-up, all patients were free of disease.

CONCLUSION

This is the largest single institution series on PNS tumors reported to date. These tumors are rare and are often misdiagnosed, given their radiological characteristics. PNS tumors have a benign course of disease and surgical resection results in favorable long-term outcomes.

Pancreatic schwannoma, an extremely rare and challenging entity: Report of two cases and review of literature

Pancreatic schwannoma is a rare benign tumor, for which the preoperative and intraoperative definitive diagnosis is quite challenging. We present the clinical, radiological and pathologic features of two primary pancreatic schwannomas identified in our pathology database over a period of 30 years at our tertiary care hospital. To better understand the clinico-pathological and radiological features of this entity, we provide a comprehensive review of 73 cases described in the English literature, along with our two cases. This review will especially focus on preoperative and intraoperative diagnosis to assess their accuracy for pancreatic schwannoma. The three most common preoperative diagnoses based on imaging for pancreatic schwannomas were cystic neoplasm (56%), pancreatic neuroendocrine tumor (29%) and mucinous cystic neoplasm (26%). Imaging could not definitely diagnose pancreatic schwannoma in any of the reported cases. To obtain a definite diagnosis before surgery, 25 cases underwent imaging-guided fine-needle aspiration (FNA)/biopsy, of which 60% were correctly reported as benign with definite diagnosis of pancreatic schwannoma in 48%. A higher diagnostic accuracy was observed in biopsies (71%) than FNA (37%). In addition, an intraoperative frozen section was carried out in 15 cases, and 47% were correctly diagnosed. Despite relatively low accuracy, preoperative histological assessment can be helpful in surgical managment. A core tissue specimen is recommended to improve the diagnostic accuracy in this setting.

Pancreatic schwannoma mimicking pancreatic cystadenoma: A case report and literature review of the imaging features

INTRODUCTION

Schwannomas, also known as neurilemmoma, are benign neoplasms that originating from Schwann cells in peripheral nerve sheaths. The head, neck, and extremities are the most common sites; however, pancreatic schwannomas are rare neoplasms. Accurate preoperative diagnosis of these tumors is very tough because of pancreatic schwannomas usually mimicking other cystic tumors. Here we present a case of pancreatic schwannoma misdiagnosed as pancreatic cystadenoma.

PATIENT CONCERNS

We presented a rare case of a 55-year-old female admitted to our hospital for abdominal distension. The physical examination and results of laboratory testing reveal no abnormalities.

DIAGNOSIS

A computed tomography (CT) scan detected a hypodense 2.4 cm × 2.6 cm mass with a clear margin at the neck of the pancreas. Pancreatic cystadenoma was strongly suspected.

INTERVENTIONS

The patient underwent robotic distal pancreatectomy with splenectomy. The gross specimen showed a pale and solid mass with a capsule.

OUTCOMES

Histological examination of the surgical specimen demonstrated a pancreatic schwannoma. Immunohistochemistry results were as follows: S-100 (+), CD117 (-), SMA (-), and Desmin (-). She was discharged on postoperative day 6 and no recurrence of the tumor happened during the 12-month follow-up.

CONCLUSION

Precise preoperative diagnosis of pancreatic schwannomas is very difficult despite the application of multiple imaging modalities. Surgery is the most effective treatment for this rare disease and the final diagnosis usually relies on pathology. Following complete tumor removal, patients with pancreatic schwannomas generally have a good prognosis.

Successful treatment of a pancreatic schwannoma by spleen-preserving distal pancreatectomy

Schwannomas are neurogenic tumors that arise from the neural sheaths of peripheral nerves. These tumors can be located in any area of the human body; the most common locations are the head, neck, trunk and extremities. Pancreatic schwannomas are very rare. Over the past 40 years, only 67 cases of pancreatic schwannomas have been reported in the English literature. Here we present a case of pancreatic schwannoma in a 62-year-old male. The tumor was revealed by ultrasound and computed tomography in the neck and body of the pancreas. An accurate diagnosis was difficult to obtain preoperatively. The patient consented to the performance of a laparotomy, and the mass was found in the neck and body of the pancreas and successfully treated using a spleen-preserving distal pancreatectomy with splenic artery and vein preservation. The procedure has only been reported in one other case of pancreatic schwannoma; here we present the second reported case. Macroscopically, the tumor was well circumscribed, gray-white in color and 3.3 cm × 2.8 cm in size. Microscopically, the tumor cells were spindle-shaped and had a palisading arrangement with no atypia, which are results compatible with a benign tumor. Both hypercellular and hypocellular areas were visible. Immunohistochemically, the tumor cells were strongly positive for S-100 protein. The tumor was definitively diagnosed as a schwannoma of the pancreatic neck and body. The patient was followed for 72 mo and has been doing well without any complications.

Retroperitoneal Malignant Schwannoma. A Case Report

The isolated retroperitoneal malignant schwannoma unassociated with Von Recklinghausen's disease is an unusual neoplasm, representing 0.01% of all retroperitoneal malignant neoplasms, with a poor prognosis, and an average survival at 5 years of 50% in patients treated by radical exeresis. At present, it is impossible, without histologic and immunohistochemical examinations, to differentiate it from other isolated retroperitoneal sarcomatous neoplasms. The authors report a case of retroperitoneal malignant schwannoma 20 cm in diameter in a 62-year-old woman surgically treated by radical exeresis. Postoperative complications were absent, and the patient, discharged from the hospital on the 12th postoperative day, died 8 months later of diffuse metastases, withouth local relapse. Despite the patient's short survival, the authors believe radical surgery to be the best therapeutic choice. Only surgery can establish a final diagnosis and can offer the best chance of survival and a significant and sometimes prolonged relief of symptomatology.

A Surgically Resected Pancreatic Schwannoma with Obstructive Jaundice with Special Reference to Differential Diagnosis from Other Cystic Lesions in the Pancreas

Pancreatic schwannomas are uncommon. About 60% of pancreatic schwannomas develop cystic lesions, and the differential diagnosis from other cystic pancreatic tumors is difficult. A 43-year-old man presented for evaluation of liver dysfunction detected during a medical checkup. Blood testing detected obstructive jaundice. A computed tomography scan revealed a well-defined polycystic tumor of about 5 cm at the pancreatic head. We performed surgical resection to treat the patient's symptoms and facilitate long-term management. Histopathological examination revealed spindle-shaped cells. Immunohistochemical studies showed S100 protein expression and the absence of CD34 and c-kit protein expression. Finally, we diagnosed a schwannoma. Pancreatic schwannoma is usually asymptomatic. The present case presented with obstructive jaundice, which is reportedly a rare symptom. Pancreatic schwannomas should be considered as a differential diagnosis of pancreatic cystic tumors. Dilatation of the pancreatic duct and the 18-fluorodeoxyglucose positron emission tomography findings are important for the differential diagnosis.

Pancreatic schwannoma: a case report and an updated 40-year review of the literature yielding 68 cases

BACKGROUND

Pancreatic schwannoma is a rare tumor. Preoperative diagnosis of pancreatic schwannoma is challenging due to its tendency to mimic other lesions of the pancreas. We describe a case of pancreatic schwannoma and present a review of the cases currently reported in the English literature to identify characteristics of pancreatic schwannoma on imaging.

CASE PRESENTATION

A 53-year-old male presented with a history of intermittent periumbilical abdominal pain and lower back pain for 1 week. Based on ultrasound (US) and computed tomography (CT) findings, we made a preoperative diagnosis of solid pseudopapillary tumor and performed a standard pancreaticoduodenectomy. Pathological examination showed that the tumor was composed of spindle cells with a palisading arrangement, and immunohistochemistry revealed strong positive staining for S-100 protein, which was consistent with a diagnosis of pancreatic schwannoma. At the 8-month follow-up visit, the patient was doing well without recurrent disease, and his abdominal pain had resolved.

CONCLUSIONS

Although pancreatic schwannoma is rare, it should be included in the list of differential diagnoses of pancreatic masses, both solid and cystic. A tumor size larger than 6.90 cm, vascular encasement, or visceral invasion should elicit suspicion of malignant transformation.

Abdominal schwannomas: review of imaging findings and pathology

Schwannomas are typically slow growing, encapsulated benign neoplasms. Visceral schwannomas are rare, and preoperative diagnosis is challenging, as they are often confused with other neoplasms even with advanced imaging studies. Surgical excision is usually needed to establish a definitive diagnosis, as pathology is the "gold standard." We review the imaging findings of abdominal schwannomas focusing on pancreatic, gastrointestinal, and retroperitoneal/adrenal schwannomas with pathology correlation. We conclude that schwannoma should be included in the broad differential diagnosis of an abdominal mass and that when it is unnecessary radical resection can be avoided.

Central pancreatectomy for pancreatic schwannoma: A case report and literature review

Schwannomas are mesenchymal tumors originating from Schwann cells in peripheral nerve sheaths. Although the tumor can be located in any part of the human body, the most common locations are the head, neck, trunk and extremities. Pancreatic schwannomas are rare. To our knowledge, only 64 cases of pancreatic schwannoma have been reported in the English literature over the past 40 years. In this paper, we present a pancreatic schwannoma in a 59-year-old female. Ultrasound, computed tomography and magnetic resonance imaging revealed the tumor located in the pancreatic body; however, accurate diagnosis was hard to obtain preoperatively and a pancreatic cystadenoma was preliminarily considered. During laparotomy, the mass was found in the body of the pancreas. An enlarged gallbladder with multiple stones was also observed. We performed central pancreatectomy, end-to-side pancreaticojejunostomy and cholecystectomy. Notably, central pancreatectomy has been reported in only one case prior to this report. The gross specimen showed a mass with a thin capsule, 1.6 cm × 1.1 cm × 1.1 cm in size. Microscopic examination showed that the tumor was mainly composed of spindle-shaped cells with palisading arrangement and no atypia, which is consistent with a benign tumor. Both hypercellular and hypocellular areas were visible. Immunohistochemical staining revealed strongly positive results for protein S-100. Finally, the tumor was diagnosed as a schwannoma of the pancreatic body. Postoperatively, the patient recovered well and left the hospital 6 d later. During the 53-mo follow-up period, the patient remained well and free of complications.

Pancreatic schwannoma: A rare case and a brief literature review

INTRODUCTION

Pancreatic schwannoma (PS) is an extremly rare benign tumor. Less than 50 cases of pancreatic schwannoma have been described in the English literature over the past thirty years.

PRESENTATION OF CASE REPORT

A 63-year-old female underwent left modified radical mastectomy 2 years ago due to breast cancer. During her routine check-up, a 65×63×55mm measured calcified, well-demarcated, cystic-mass having septations and calcifications that localized to the pancreatic head was detected by abdominal computerized tomography. She was asymptomatic and her tumor markers were in normal ranges. A standard Whipple procedure was performed, and the histo-pathological diagnosis of the resected specimen was reported as ancient schwannoma with clear surgical margins. Patient's postoperative course was eventful. She had a biliary leakage after surgery which was managed conservatively. She is under follow-up.

DISCUSSION

Pancreatic schwannoma also known as neurilemoma or neuroma is a slowly growing, encapsulated, mostly benign tumor with smooth well-delineated margins that originates from myelin producing schwann cells located on the nerve sheath of the peripheral epineurium of either the sympathetic or parasympathetic autonomic fibers. PS's are extremly rare. The head of pancreas being involved in the vast majority of cases (40%), followed by its body (20%). Management of pancreatic schwannomas remains largely controversial. Both enucleation and radical surgical resections have revealed great therapeutic efficiency. with a well prognosis without recurrences.

CONCLUSION

Although rare, PS's should be considered in the differential diagnosis of the other solid or cystic masses of the pancreas.

Enlarging Pancreatic Schwannoma: A Case Report and Review of the Literature

A 72-year-old female presented with dyspepsia for 2 years and an incidental mass in the head of the pancreas on abdominal computed tomography (CT) scan. Patient had multiple negative endoscopic ultrasound guided biopsies. She was followed up for 3 years with serial imaging until an abdominal CT scan showed an increase in size of the pancreatic mass. Physical examination was unremarkable. Laboratory tests including tumor markers were normal. Given the enlarging size of the mass and its impingement on the portal vein, the consensus was to proceed with surgery. Histology revealed a 3.5 cm mass showing a spindle cell neoplasm with mild atypia. The lesion was well defined and nerve tissue was noted at the periphery. On immuno-stains, the spindle cells were positive for S-100 protein and negative for pan-cytokeratin, CD-34, CD-117, smooth muscle actin and Melan A, consistent with the diagnosis of a pancreatic schwannoma.

A case of pancreatic schwannoma - The features in imaging studies compared with its pathological findings: Report of a case

Pancreatic schwannoma is a very rare tumor that tends to be confused with other pancreatic tumors preoperatively. We report a case of schwannoma of the pancreatic head. A 40-year-old woman was admitted to our hospital for treatment of a pancreatic tumor which was found by medical checkup. It was a well-defined solid tumor exhibiting heterogeneous enhancement with some necrotic foci on contrast-enhanced computed tomography (CT) and on magnetic resonance imaging (MRI). Angiography and CT during arteriography revealed the main feeding arteries of the tumor to be the posterior and anterior superior pancreaticoduodenal arteries. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) showed accumulation of FDG in the tumor with a maximum standardized uptake value of 3.6. We diagnosed a solid pseudopapillary neoplasm or a pancreatic neuroendocrine tumor preoperatively and performed pylorus-preserving pancreaticoduodenectomy. The tumor had well a well-defined capsule and was composed of a large solid portion containing spindle cells and a smaller hemorrhagic portion containing hypocellular stroma, and diagnosed as pancreatic schwannoma by immunohistochemistry. In this case, CT during arteriography was useful in determining the origin of the tumor. MRI reflected the pathological features of the tumor. The most important finding was that FDG-PET showed abnormal accumulation of FDG in the benign pancreatic schwannoma.

Pancreatic tail schwannoma in a 44-year-old male: a case report and literature review

Pancreatic schwannomas are exceedingly uncommon neoplasms. According to a recent study in 2012, less than 50 cases of pancreatic schwannoma have been described in the English literature over the past thirty years. The vast majority of pancreatic schwannomas take place in the head and body of pancreas, respectively. Herein, we report the case of pancreatic tail ancient schwannoma in a 44-year-old man who presented with a 4-month history of epigastric pain. On physical examination, epigastric region was moderately tender to palpation without evidence of a palpable mass. All laboratory tests were normal. Contrast-enhanced computed tomography (CT) scan showed a 9.2 × 9.5 × 11.5 cm, huge, and well-defined left suprarenal mass arising either from adrenal gland, pancreas, or retroperitoneum. The mass demonstrated mild heterogeneous enhancement with central cystic/necrotic area. No evidence of distant metastasis was identified. At laparoscopy, the mass was noticed to originate from pancreatic tail. Patient underwent surgical resection of pancreatic tail. Microscopic and immunohistochemical examination of the pancreatic tail specimen showed ancient schwannoma. Patient received no adjuvant therapy. At a postoperative 6-month followup, patient was completely asymptomatic and CT scan imaging showed no evidence of tumor recurrence. Moreover, a literature review on pancreatic schwannomas is presented.

Pancreatic schwannoma: Case report and an updated 30-year review of the literature yielding 47 cases

Pancreatic schwannomas are rare neoplasms. Authors briefly describe a 64-year-old female patient with cystic pancreatic schwannoma mimicking other cystic tumors and review the literature. Databases for PubMed were searched for English-language articles from 1980 to 2010 using a list of keywords, as well as references from review articles. Only 41 articles, including 47 cases, have been reported in the English literature. The mean age was 55.7 years (range 20-87 years), with 45% of patients being male. Mean tumor size was 6.2 cm (range 1-20 cm). Tumor location was the head (40%), head and body (6%), body (21%), body and tail (15%), tail (4%), and uncinate process (13%). Thirty-four percent of patients exhibited solid tumors and 60% of patients exhibited cystic tumors. Treatment included pancreaticoduodenectomy (32%), distal pancreatectomy (21%), enucleation (15%), unresectable (4%), refused operation (2%) and the detail of resection was not specified in 26% of patients. No patients died of disease with a mean follow-up of 15.7 mo (range 3-65 mo), although 5 (11%) patients had a malignancy. The tumor size was significantly related to malignant tumor (13.8 ± 6.2 cm for malignancy vs 5.5 ± 4.4 cm for benign, P = 0.001) and cystic formation (7.9 ± 5.9 cm for cystic tumor vs 3.9 ± 2.4 cm for solid tumor, P = 0.005). The preoperative diagnosis of pancreatic schwannoma remains difficult. Cystic pancreatic schwannomas should be considered in the differential diagnosis of cystic neoplasms and pseudocysts. In our case, intraoperative frozen section confirmed the diagnosis of a schwannoma. Simple enucleation may be adequate, if this is possible.

Malignant schwannoma of the pancreas involving transversal colon treated with en-bloc resection

Pancreatic schwannoma is a very uncommon tumor of the pancreas, with only 27 cases reported. Most pancreatic schwannomas are benign, with only four malignant tumors reported. We describe a case of giant malignant schwannoma of the pancreatic body and tail, which involved the transverse colon. The tumor was treated successfully with en bloc distal splenopancreatectomy and colon resection. This is believed to be the first reported radical operation for malignant schwannoma of the pancreatic body, with infiltration of the transverse colon, with excellent long-term results. The patient is alive and well 28 mo after the operation. The authors conclude that pancreatic schwannomas should be considered in the differential diagnosis of cystic neoplasms of the pancreas, although the diagnosis can only be confirmed by microscopic examination. In the case of the benign tumors, local excision is adequate, but in the case of malignant schwannoma, oncological standards must be fulfilled.

Pancreatic schwannoma: literature review

Pancreatic schwannoma is a rare neoplasm. Accurate preoperative diagnosis remains difficult, but computed tomography (CT) scanning and magnetic resonance imaging (MRI) help to establish the diagnosis, and definitive diagnosis requires immunohistochemical examination. Cystic pancreatic schwannomas should be considered in the differential diagnosis of cystic neoplasms and pseudocysts. Simple enucleation may be adequate for pancreatic schwannoma. In this report, we examine a case of benign pancreatic schwannoma in a 56-year-old woman. She was being evaluated for an ovarian teratoma, and an 8-cm cystic mass was incidentally found in the head of the pancreas. She underwent a pylorus preserving Whipple procedure with bilateral oopherectomy. Only 37 cases have been reported in the English literature. We present a thorough review with an emphasis on the clinical presentation, diagnostic modalities, and treatment options in the management of this rare clinical entity.

Pancreatic schwannoma: report of a case

Among pancreatic neoplasms, pancreatic schwannoma is quite rare. We report a case of solitary pancreatic schwannoma, plus a literature review of this tumor. A 71-year-old woman was diagnosed by abdominal ultrasonography as having a pancreatic tumor and was hospitalized in our department at Kumamoto University Hospital on January 26, 2006. Abdominal computed tomography, magnetic resonance imaging, and endoscopic ultrasonography all showed this tumor, which was located in the body of the pancreas, to have cystic and solid components, and with a septum in the cystic part of the lesion. The tumor, preoperatively identified as a mucinous cystic neoplasm, was clearly separated from the normal pancreatic parenchyma. We performed a spleen-preserving distal pancreatectomy with a lymph node dissection on February 7, 2006. A histopathological examination of the resected specimen by means of hematoxylin and eosin revealed the tumor to consist of two parts: one with a compact spindle cell pattern (Antoni type A), and the other showing degeneration of fat (Antoni type B). We also found positive results for immunohistochemical staining for S-100 and vimentin. These findings confirmed the tumor's classification as a pancreatic schwannoma.

Analysis of 50 cases of pancreatic schwannoma

AIM: To analyze the incidence of pancreatic schwannoma and investigate its diagnosis and treatment.

METHODS: A retrospective study of clinical data from 50 patients with pancreatic schwannoma.

RESULTS: The lesion was located in the head of pancreas in 25 patients, the body in 9 (18%), the body and tail in 6, the tail in 5, the head and body in 2, the neck in 1, and the location was not specified in 2 patients. Solid tumors were found in 18 patients, cystic tumors in 25, and the nature of the tumor was not specified in 7 patients. Forty-nine patients received operative therapy. Thirteen patients underwent a Whipple operation, 12 distal pancreatectomy, 12 local resection, 8 simple enucleation, and in 2 patients the surgical procedure was not specified. The tumor in 1 patient was unresectable. One patient underwent biopsy. One patient refused surgery. The longest follow-up was 9 years, and there have been no reports of local recurrence or metastasis.

CONCLUSION: Preoperative diagnosis of pancreatic schwannoma is difficult. Definite diagnosis depends on pathological examination. Benign tumors can be effectively treated by local excision but those with malignancy should be treated by simple enucleation. Intraoperative frozen sections are useful for determining which kind of operation should be undertaken.

Clinical characteristics, treatment, and outcome of pancreatic Schwannomas

This article involves the study of a patient with a rare benign schwannoma in the body of the pancreas. After reviewing 39 patient cases previously reported in the literature, a discussion of the schwannoma with regard to clinical presentation, diagnosis, and treatment is examined. A review of the patient's chart was performed along with a review of the literature using a Medline search. Translations were performed whenever necessary. There are 23 reports of 29 patient cases of pancreatic schwannomas in English and European literature and one report of 10 patient cases in the Japanese literature. The mean age was 57.75 years (range 32-89) and the male-to-female (M:F) ratio was 17:23. The mean reported size was 8.79 cm. The lesion was located in the head in 16 patients (40%), the body in 8 patients (20%), the body and tail in 8 patients (20%), the tail in 6 patients (15%), the head and body in 1 patient (2.5%), and the location was not specified in 1 patient (2.5%). Of the English and European patients, 11 out of 30 patients (36.7%) exhibited solid tumors and 14 out of 30 patients (46.7%) exhibited cystic tumors. The majority of the tumors (35 out of 40) were benign, but there were five reported malignancies. There were no deaths or recurrences reported with a follow-up of 18.68 months +/- 24.09 (range 3-108 months). Pancreatic schwannomas are rare, and the preoperative diagnosis is difficult. Intraoperative frozen section can confirm the diagnosis of a benign schwannoma. Enucleation of the tumor from the surrounding parenchyma is recommended, if possible. Patients undergoing resection indicate an excellent long-term prognosis.

Cystic schwannoma of the pancreas

Intrapancreatic schwannoma is a rare neoplasm. We report a case of a 46-year-old man with a cystic schwannoma in the head of the pancreas. This tumor, based on clinical manifestations and radiologic features, was initially suspected to be a cystic mucinous tumor of the pancreas or a pseudocyst. Histologically, the tumor was a typical schwannoma with cyst formation caused by degenerative changes. Immunostaining showed the tumor cells to be strongly and diffusely positive for S-100 protein, vimentin, and CD56, and negative for cytokeratin AE1/AE3, desmin, smooth muscle myosin specific, CD34, and CD117, which support the diagnosis of schwannoma. Cystic schwannoma is a rare neoplasm occurring in the pancreas and should be considered in the differential diagnoses for patients presenting with pancreatic cystic lesions.

Pancreatic schwannoma: an uncommon but important entity

The literature contains five single case reports of pancreatic schwannoma-two of the five occurred in patients with von Recklinghausen's disease, and three of the five proved malignant. Within a 3-month period, we resected benign pancreatic schwannomas in two patients without von Recklinghausen's disease. Both patients presented with pain that led to the discovery of a complex pancreatic mass on abdominal CT scan. Pancreatic schwannoma should be included in the differential diagnosis of cystic or solid pancreatic abnormalities on imaging studies.

Malignant peripheral nerve sheath tumor of the pancreas with perineurial cell differentiation

The authors report a malignant peripheral nerve sheath tumor (MPNST) that developed in the body of the pancreas of a 76-year-old woman. The well-demarcated tumor, 4.5 x 3.5 cm in size, was composed of spindle-shaped cells arranged in a storiform pattern or sweeping fascicles. Ultrastructurally, the tumor cells had elongated cytoplasmic processes with numerous pinocytotic vesicles, and were covered with discontinuous basal lamina-like substances. Immunohistochemically, tumor cells were diffusely positive for epithelial membrane antigen, vimentin, and CD34, but negative for S-100 protein and Leu 7. It was therefore concluded that the tumor was a MPNST with perineurial cell differentiation. Primary MPNST of the pancreas is extremely rare and the immunohistochemical and ultrastructural studies are necessary for its diagnosis.