The schwannoma: an uncommon type of cystic lesion of the pancreas

Schwannomas of the pancreas are rare and their number is lower than is usually reported in the literature since some were probably neurofibromas. We report a further case characterized by cystic feature, clinically mimicking a pancreatic pseudocyst. Cystic lesions of the pancreas also comprise the schwannomas, both benign or malignant, as has been previously reported and is stressed by the present case. Cyst formation characterizes many diseases of the pancreas, both neoplastic and not. Difficulties in the differential diagnosis of cysts are fortunately reduced by the preponderance of pseudocysts (i.e. non-neoplastic cysts) and, among neoplastic ones, of cystadenomas and cystadenocarcinomas. As a consequence, uncommon cystic neoplasms are neglected and very often misdiagnosed. We reported a case of solitary schwannoma mimicking a pancreatic pseudocyst, interesting both because of its rarity and because of its cystic feature which was previously reported in the literature but not emphasized.     

Catalytic efficiency of expressed aromatase following site-directed mutagenesis

A solid and cystic tumor (SCT) of the pancreas occurring in a 35-yr-old male is reported. Cut sections of the specimen revealed a solid, ill-defined mass measuring 2.5 x 2.3 x 2.0 cm, without cystic or necrotic changes. Histologically, the solid tumor consisted of small, round acidophilic cells invading the surrounding pancreatic parenchyma. The tumor cells were positive for alpha-1-antitrypsin and neuron-specific-enolase. Ultrastructural studies revealed clear nuclei with no zymogen, but immature secretory granules in the cytoplasm of the tumor cells, which had a junctional complex-like structure. These findings were consistent with the so-called solid and cystic tumor of the pancreas. There was neither a capsule surrounding the tumor nor a papillary structure, known to be characteristic findings of the SCT tumor. The small tumor reported in the present article might represent an early-stage SCT of the pancreas.     

Cystic mesothelioma of the peritoneum

We report a case of cystic mesothelioma of the peritoneum (CMP), a rare tumor. The magnetic resonance imaging (MRI) findings and the histochemical features were studied. The patient was an 18-year-old women who presented with upper abdominal pain. Abdominal ultrasonography and computed tomography showed a well defined cystic mass with a solid papillary projection in its lumen. MRI of the cyst showed high intensity on T2- and proton weighted images and low intensity on T1-weighted images, and the solid projection showed low intensity on T2- and proton-weighted images and slight low intensity on T1-weighted images, on which it was well enhanced. The lesion was suspected to be a benign cyst, such as a hemangioma, lymphangioma, or a splenic or pancreatic cyst. Complete surgical resection was performed. The resected specimen consisted of a unilocular cystic mass, with a solid projection, weighing 260 g and measuring 10 cm in diameter. The final diagnosis, arrived at by histopathological examination, was low-grade malignant CMP. The tumor cells were strongly positive for keratin, weakly positive for vimentin, and negative for epithelial membranous antigen. The patient is now well and symptom-free with no recurrence 19 months after operation. CMP is a rare tumor; only 12 cases have previously been reported in Japan.     

Benign schwannoma of the liver with cystic changes misinterpreted as hydatid disease

The rare event of a benign mesenchymal tumor of the liver is described since its cystic transformation resembled hydatid disease through the presence of Echinococcus. Ultrasound and computerized tomography showed a cystic mass within the liver of a 57 year-old woman with upper abdominal pain. This was interpreted as hydatid disease and an evacuation procedure was performed. The histopathology of a minute specimen was interpreted as consistent with chronic inflammation in a cyst wall. Five years later, a recurrence of the parasite was suspected, and complete excision of the mass and resection of a bile fistula was performed. The histopathological examination revealed a large benign schwannoma with regressive cystic changes, proven by positive immunoreaction for the neurogenic marker S-100 protein. Revision of old paraffin blocks of tissue taken during the first operation was able to retrospectively confirm the identical tumor by the same markers. Occurrence of schwannomas in parenchymatous organs or the retroperitoneum is extremely rare and may lead to asymptomatic growth with cystic changes, causing considerable difficulties in imaging procedures. Overall, the primary complete excision of cystic masses within the liver seems to be the best approach in discovering their real nature and to ultimately cure them.     

Ancient schwannoma of the submandibular gland: a case report

Schwannomas (neurilemmomas) are neurogenic tumors that arise from the Schwann cells of the neural sheath. They are most often benign and solitary. Extracranial schwannomas are rare, and can be mistaken for metastatic disease or other non-neurogenic tumors. Ancient schwannoma is a rare variant of schwannoma with a course typical of a slow-growing benign tumor. Histologically, it can be confused with a malignant mesenchymal tumor. An unusual case of an ancient schwannoma of the submandibular gland is reported. The clinical, histological and surgical aspects of this tumor are discussed, and the literature regarding this rare entity is reviewed.     

Gastric schwannoma

A rare case of gastric schwannoma is reported. A 36-year-old woman whose endoscopy showed a mucosa tumor, biopsy findings were suggestive for leiomyoma. Diagnosis was made only with postoperative histology that revealed the benign schwannoma. Immunohistochemical staining showed positivity for S-100 protein and the neuron specific enolase, schwannoma is often associated with Von Recklinghausen's disease. Surgical resection is recommended as their malignant potentiality. Gastric and small intestine localizations are often with bleeding. They also represent almost the 24% of all gastrointestinal stromal tumors (GIST) and the 4% of all primary retroperitoneal tumors.     

Adenocarcinoma arising in a tailgut cyst: report of a case

We report herein the unusual case of a 66-year-old woman found to have adenocarcinoma arising in a tailgut cyst. The patient had been observed for 6 months following the discovery of a presacral cystic mass measuring 10 x 9 cm for which she had refused surgery. The serum tumor marker, carcinoembryonic antigen, became slightly elevated, and diagnostic imaging distinctly revealed a tumorous lesion with papillary projection into the cyst lumen. The cystic mass was then excised through the transsacral approach. The pathological findings were compatible with moderately differentiated adenocarcinoma arising in a tailgut cyst. This entity is extremely rare, and only six cases, including our own, have been reported in the English literature. Early complete excision is advised because it is almost impossible to determine for certain whether presacral cystic masses are benign or malignant prior to surgery.     

Serous cystadenoma of the pancreas with invasive growth: benign or malignant?

We describe a case of serous cystadenoma, that invaded a lymph node and adipose tissue. Preoperatively, the cystic lesion of the pancreas was diagnosed as a serous cystadenoma and subsequently the patient, a 71-yr-old woman, underwent distal pancreatectomy with splenectomy. Macroscopically, a greyish white, externally lobulated and partly ovoid tumor, measuring 12 x 8.5 x 5 cm, occupied the pancreatic body and tail extensively. In cross-section, multiple nodules were observed, which measured from 0.5 to 3 cm in diameter, were separated by hyalinized fibrous septa and were filled with numerous microcysts. Light microscopic findings were consistent with those for serous cystadenoma. At the splenic hilus, the tumor was found to have invaded the lymph node and adipose tissue. Based on the clinicopathological features of the six reported cases, including the present case (which behaved in a malignant fashion in terms of pathological findings of invasion or metastasis), serous cystadenoma should be regarded as having the potential for malignant growth.     

Age-related changes of electrocardiographic wave

OBJECTIVE: Cystic tumors of the adrenal gland are uncommon, but are being increasingly more frequently diagnosed during routine radiological evaluation as "incidentalomas". We discuss the differential diagnosis, therapeutic approach and the existing controversies concerning the management of this tumor type. METHODS: Two additional cases of adrenal pseudocyst in two women aged 47 and 38 years are presented. In one case the tumor was discovered incidentally, whereas the other case presented with acute pain arising from intracystic hemorrhage. RESULTS: The fist patient had a cystic tumor of 8 cm with some inner walls. Fine needle aspiration biopsy revealed a benign cystic lesion of the right adrenal gland. At laparotomy, an 8.5 x 4.5 cm multiloculated cystic lesion was excised. The second patient presented with abdominal pain due to intracystic hemorrhage. A Doppler US did not disclose any vessel inside the lesion. We performed a lumbotomy and excised a 7.5 x 6 cm cystic tumor located in the right adrenal gland. Both lesions were diagnosed as adrenal pseudocyst; the second case was a hemorrhagic one. CONCLUSIONS: The therapeutic approach in adrenal cystic tumors can be based upon the radiological and cytological findings since malignant cystic tumors are uncommon. A clear liquid and a negative cytology practically discard malignant tumors. Furthermore, cystic adenocarcinomas are usually large and the cystic liquid is cloudy with abundant cellularity. Surgical treatment is justified in the symptomatic, big or complex tumors (mixed, non-homogeneous).     

Diagnosis of pancreatic carcinoma: role of FDG PET

OBJECTIVE: The purpose of this study was to investigate the role of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in differentiating benign from malignant disease in patients with possible pancreatic malignancy. SUBJECTS AND METHODS: All patients with a possible diagnosis of pancreatic carcinoma based on CT or ERCP findings were eligible for inclusion in this prospective study. PET imaging of the abdomen was performed in 37 patients and was interpreted as positive if FDG activity in the pancreas exceeded background activity and as negative if activity was less than or equal to background activity. Semiquantitative analysis was performed by calculating a standardized uptake ratio. Studies were reviewed independently by two radiologists, and results were correlated with biopsy results and with CT and ERCP findings. Sensitivity and specificity of FDG PET for revealing pancreatic malignancy was determined. RESULTS: FDG activity in the pancreas was increased in 24 patients, and adenocarcinoma was diagnosed in 22 of these patients (92%). Two patients (8%) with increased activity had benign disease, including one patient with chronic pancreatitis who showed no evidence of tumor at laparotomy and one patient with a mucinous cystic tumor who showed no malignant features at laparotomy. FDG uptake was low or normal in 13 patients, 10 of whom (77%) had benign disease. FDG uptake was also low in three patients with adenocarcinoma, whose tumor size ranged from 2 to 4 cm in diameter. The mean standardized uptake ratio value for malignant disease was 5.1 (range, 1.0-10.1) and for benign disease was 1.9 (range, 0.0-5.8) (p < .001). The sensitivity of FDG PET for revealing malignant disease in the pancreas was 88% and the specificity was 83%. CONCLUSION: FDG PET is a sensitive and specific noninvasive technique for the diagnosis of pancreatic malignancy.     

Diffuse plane xanthoma: clinicopathologic study of 8 cases

We report a 17-year-old woman who had two synchronous solid and cystic tumors of the pancreas (SCTP) detected by abdominal echography and computed tomography. There was a 6 x 5 cm mass in the pancreatic body and a 3 x 3 cm mass in the tail, with the two lesions being separate. No distal metastases were detected. The resected tumors consisted of solid and cystic components and both were well demarcated with fibrous capsules. The larger tumor was predominantly solid and the smaller one was mostly hemorrhagic. On microscopy, the tumor cells were small, eosinophilic, and arranged, in part, like pseudorosettes. The tumor cells were immunohistochemically positive for alpha-1 antitrypsin, neuron-specific enolase, and synaptophysin. The final diagnosis was SCTP arising synchronously and independently at two sites. As far as we know, only one case of multicentric SCTP has been reported previously. Local recurrence of SCTP suggests the possibility of multicentric occurrence, and we believe that reports of such cases may increase in the future with advances in echography and computed tomography.     

Diagnosis of mucin-producing tumor of the pancreas by balloon-catheter endoscopic retrograde pancreatography--compression study

The procedure of choice for the treatment of mucin-producing pancreatic tumor (MPPT) remains controversial, since it includes not only malignant but also benign lesions. The purpose of the present study was to characterize 53 consecutive cases of MPPT and to elucidate the characteristics of benign or malignant MPPT according to the findings of an improved method of endoscopic retrograde pancreatography (ERP), namely balloon-catheter ERP-compression study (balloon ERP-CS), as well as endoscopic ultrasonography (EUS), in comparison with a histological examination. There were 37 male and 16 female cases with a median age of 63+/-11 (mean+/-SD). The balloon ERP-CS was performed in all cases, and the obtained pancreatograms were classified into two types: Main Duct type and Branch Duct type. The latter was further divided into subtypes A and B. The Branch Duct A type showed only cystic dilatation of the branch duct. If the main pancreatic duct downstream to a cyst showed more than a 5 mm dilatation, this was classified as a Branch Duct B type. Seventeen out of 19 Main duct types (89%) were histologically diagnosed as neoplasms including 13 lesions of cancer and 4 of adenoma. All the Branch Duct A type cases were diagnosed as hyperplasias. 23 Branch Duct B type cases contained 7 cancers, 8 adenomas, and 8 hyperplasias. In the Main Duct type, benign or malignant, the diagnostic ability of balloon ERP-CS was calculated as sensitivity 100%, specificity 40%, and accuracy 84%; in the Branch Duct type, sensitivity 73%, specificity 86%, and accuracy 82%. On EUS, it was found that the size of the tumor in the cyst, with respect to the maximum diameter as well as height, correlated well with the grade of malignancy. All tumors (n=35) greater than 20 mm in diameter were found to be cancerous. These findings indicate that the MPPT is highly suggestive of neoplasms when the dilatation of the main pancreatic duct is detected by balloon ERP-CS and when, in a case without dilatation of the main pancreatic duct, a nodular lesion greater than 10 mm in diameter is identified in the cyst by balloon ERP-CS as well as EUS. Our current patient management strategy for operations is as follows: Main Duct type patients and Branch Duct type patients with a nodular defect detected by balloon ERP-CS and with an elevation of more than 10 mm in EUS should have an operation. Other Branch Duct type patients without main pancreatic duct dilatation are followed up by balloon ERP-CS.     

Histologic and biologic patterns of microscopic pancreatic ductal adenocarcinomas detected incidentally at autopsy

BACKGROUND: The major clinical problems with pancreatic carcinoma are its silent course and late, fatal clinical manifestation. The results of treatments of small pancreatic carcinomas (<2 cm in greatest dimension) have led to the assumption that the detection of these cancers at earlier stages would lead to better survival and possible cure. Currently, there is no information about the histologic and biologic patterns of early stage pancreatic carcinoma, and the available data on incidentally detected tumors are fragmentary. The authors observed two incidental microscopic pancreatic ductal adenocarcinomas in female patients who died of advanced gastric carcinoma (Case 1) and renal carcinoma (Case 2). METHODS: The pancreatic lesions were examined histologically in serial sections and immunocytochemically for islet cells. Microdissection was performed so that the lesions could be examined for c-Ki-ras mutation. RESULTS: In Case 1, the pancreatic lesion was composed of cystic and solid components. The cystic component consisted of four small cysts compatible with a mucinous cystic tumor and showed no invasion. The solid component was a well-differentiated adenocarcinoma that occupied a 4 x 2 mm area. In Case 2, the pancreatic lesion contained two small, separate cysts, one of which was surrounded by two apparently separate, invasive adenocarcinomas 2.6 x 0.7 mm and 1.2 x 0.5 mm in greatest dimension. There was invasion of pancreatic islets and perineural spaces in both cases; and in Case 2, there was invasion of peripancreatic fatty tissue. In both cases, the epithelia of the cystic components and tumors showed mutation of the c-Ki-ras oncogene at codon 12, with GGT-to-GAT transition. CONCLUSIONS. Pancreatic carcinoma seems to occur under occult circumstances and maintain a silent course. Even in its early developmental stage, the cancer is invasive, primarily affects islets and nerves, and exhibits mutation of the c-Ki-ras oncogene. These findings call for urgency in the development of preventive modalities.     

The SOCS proteins: a new family of negative regulators of signal transduction

An asymptomatic tumor in the pelvis was incidentally found by ultrasonography in a 67-year-old woman while being examined after presenting with a common cold. Further examinations revealed a presacral cystic tumor, which measured 10 x 12cm in size. The cyst was thus removed in the normal manner for such cases. The pathological diagnosis was an epidermoid cyst. An analysis of 15 other cases previously reported in the literature indicated that large epidermoid cysts should normally be excised through an abdominal approach alone, provided that the tumor is benign.     

Giant plexiform schwannoma: a report of two cases with soft tissue and visceral involvement

We report two cases of massive, solitary, plexiform schwannoma. One was a 9-cm subcutaneous lesion on the hip of a 72-year-old man who had become aware of the slow-growing tumor 50 years earlier; the other is the first reported plexiform schwannoma to arise in a visceral organ: it arose in the ascending colon of a 54-year-old man and exhibited a dumbbell configuration with submucosal and subserosal components. Neither patient had neurofibromatosis or schwannomatosis. Both tumors were well-circumscribed and multinodular, and both showed a plexiform architecture. Microscopically, the nodules were composed primarily of Antoni A tissue, replete with nuclear palisading and Verocay bodies. Examination by immunohistochemistry and electron microscopy demonstrated the features of well-differentiated Schwann cells; nodules were surrounded by attenuated, residual perineurium. Both patients followed a benign clinical course, without recurrence or metastasis. Neither the large tumor size nor the unusual locations affected the biologic behavior of these neoplasms. A massive plexiform schwannoma must be distinguished from a malignant peripheral nerve sheath tumor and from a plexiform neurofibroma, a tumor prone to malignant transformation.     

Thoracoscopic resection of schwannoma: a report of two cases

We have performed thoracoscopic resection of schwannoma without intraspinal extension in two asymptomatic cases confirmed by chest roentgenogram and computed tomography: the case 1 with the tumor as large as 4.0 x 4.0 x 3.5 cm found in the paravertebral fifth Intercostal space, the case 2 with the tumor as large as 3.2 x 2.5 x 1.8 cm found on the first rib in contact with the supreme intercostal vein. In the operation of case 1, the dilated fifth intercostal vein in contact with the tumor which could not be controlled by Endo-Clip was doubly ligated by the use of Knot-Pusher. The tumor was successfully dissected from the chest wall and proved to arise from the fifth intercostal nerve. The tumor was brought into Endo-Pouch and extracted through one of the skin incisions which was minimally enlarged to accommodate the pouched lesion. In the operation of case 2, curved forceps facilitated the procedure because the tumor located near the apex of thorax. The tumor was found to originate from sympathetic nerve and removed through the minimally enlarged incision as case 1. We conclude as the following. The benign tumor found in the mediastinum or the chest wall is amenable to thoracoscopic treatment. In thoracoscopic procedure, as the operation under thoracotomy, we must acquire skills of standard operative technique, i.e., suture or ligation, because those skills are necessary when Endo-Clip or Endo-GIA cannot be used. The skin incision should be minimally enlarged finally when the specimen is extracted to minimize operative intervention.     

Detection of paraneoplastic anti-neuronal autoantibodies on paraffin-embedded tissues

Although the detection of pancreatic carcinoma has been considerably improved by recently developed imaging procedures, differential diagnosis between cancer and benign tumor masses, as well as lymph node staging, is still difficult. In vivo evaluation of regional glucose metabolism by means of positron emission tomography (PET) and fluorine-18-labelled fluorode-oxyglucose (FDG) is a new approach utilizing metabolic instead of morphological tumor properties for diagnosis. PATIENTS AND METHODS. A total of 85 patients with suspected pancreatic carcinoma were investigated by FDG-PET prior to surgery. Static PET scans were evaluated visually as well as quantitatively, taking increased FDG uptake as a sign of malignancy. PET results were correlated with intraoperative findings and histopathology of surgical specimens. RESULTS. Forty-seven out of 55 (85%) malignant tumors and 23 out of 30 (77%) benign lesions were correctly classified by PET. Lymph node metastases were present in 31 patients, 19 of them (61%) positive in PET. In 7 our of 13 (54%) patients with liver metastases, PET detected hypermetabolic lesions. False-negative findings were mainly due to disturbance of glucose metabolism in diabetic patients, while most false-positive results could be attributed to acute inflammatory lesions in chronic pancreatitis. CONCLUSIONS. Our results indicate that classification of pancreatic masses can be improved by use of FDG-PET, which might lead to a reduction of unnecessary laparotomies in patients with benign or incurable disease.     

Pseudocoarctation of the abdominal aorta

Cystic insulinomas are rare, with only three cases having been reported in the literature. It is not difficult to determine the site of such neoplasms, as cystic insulinomas are usually 4-10 cm in diameter. We report a patient with a histologically confirmed cystic insulinoma. This case is unique because of the small size (1.3 cm) of the tumor. Arterial stimulation venous sampling was useful for localizing and distinguishing this tumor from other pancreatic lesions.     

Schwannoma of the obturatorius nerve as differential diagnosis in cystic adnexa tumors

We report on a case of benign retroperitoneal schwannoma involving the obturator nerve. Discussing the difficulties of diagnosis and treatment the following became clear: 1.) Clinical examination, ultrasound and computed tomography are not helpful to differentiate a retroperitoneal schwannoma from a cystic ovarian tumour; this problem can perhaps be overcome by MR imaging. 2.) The diagnosis should be borne in mind in cases of retroperitoneal tumours of unclear origin. Appropriate surgery is necessary to avoid nerve damage and paralysis.