Mixed acinar-endocrine carcinoma arising in the ampulla of Vater

A case of acinar cell carcinoma originating from the accessory papilla of the duodenum

CASE PRESENTATION

A 61-year-old female was referred to our hospital with a neoplastic lesion in the duodenum. Computed tomography with contrast enhancement revealed a 10-mm tumor in the duodenum. Upper gastrointestinal endoscopy revealed a submucosal tumor-like lesion in the descending part of the duodenum. Endoscopic ultrasound revealed a well-defined hypoechoic tumor. Biopsy and immunohistochemical findings including negative Synaptophysin and Chromogranin A staining and positive Trypsin and BCL10 staining suggested a carcinoma with acinar cell differentiation. Pancreatoduodenectomy was performed, and the resected specimen had a 15-mm solid nodule in the submucosal layer of the duodenum. Pancreatogram of the resected specimen revealed a tumor localized in the accessory papilla region. In histopathological examination, the tumor was found in the submucosa of the duodenum with pancreatic tissue present nearby, and these were separated from the pancreatic parenchyma by the duodenal muscle layer. These findings led to a diagnosis of acinar cell carcinoma originating from the accessory papilla of the duodenum.

CONCLUSION

Acinar cell carcinoma originating from the accessory papilla of the duodenum is exceptionally rare, with no reported cases to date. The origin was considered to be pancreatic tissue located in the accessory papilla region.

Mixed adenoneuroendocrine carcinoma of the ampulla of Vater: Three case reports and a literature review

Mixed adenoneuroendocrine carcinoma is defined as a tumor with a mixture of adenocarcinoma components and neuroendocrine neoplasm components. Each of these two components of mixed adenoneuroendocrine carcinoma accounts for at least 30% of all tumors. Mixed adenoneuroendocrine carcinoma might be located in the ampulla of Vater, a very rare location compared to other organs. Thus, its treatment and prognosis plans have not been established yet. We report three cases of mixed adenoneuroendocrine carcinoma occurring in the ampulla of Vater. Each patient had a different clinical course. In general, difficulty in preoperative diagnosis, risk of early recurrence, and poor disease course were main hallmarks of mixed adenoneuroendocrine carcinoma arising from the ampulla of Vater. However, one patient in this case report survived although she did not receive adjuvant chemotherapy due to her old age. Therefore, it is important to establish a careful treatment strategy for mixed adenoneuroendocrine carcinoma arising from the ampulla of Vater.

Management and outcomes of mixed adenoneuroendocrine carcinoma of the ampulla of Vater: A systematic review and pooled analysis of 56 patients

BACKGROUND

Tumors of mixed neuroendocrine and nonneuroendocrine histology are classified as collision, combined, or amphicrine and can occur in most organs, including the hepato-pancreato-biliary tract. Given the rarity of mixed adenoneuroendocrine carcinoma (MANEC) of the ampulla of Vater, the patient characteristics, management, and outcomes remain unclear. We sought to systematically review the worldwide literature on ampullary MANECs.

METHODS

Eligible studies were identified through a systematic search of the MEDLINE (via PubMed), Scopus, and Cochrane Library databases (end-of-search-date: January 5th, 2022), according to the PRISMA 2020 statement.

RESULTS

A total of 39 studies reporting on 56 patients with ampullary MANEC were included. The median age was 63.0 (interquartile range [IQR]: 51.0-69.0) years and 55.6% were male (n = 25/45). Most had combined tumors (64.4%; n = 29/45), followed by collision (24.4%; n = 11/45), and amphicrine tumors (11.1%; n = 5/45). More than half had lymph node metastasis (56.8%; n = 25/44), yet only 7.9% had distant metastasis (n = 3/38). Tumor resection (i.e., mostly pancreaticoduodenectomy) was performed in 96.3% (n = 52/54), followed by adjuvant chemotherapy in 61.8% (n = 21/34). Nearly half experienced disease recurrence (47.2%; n = 17/36) over a median follow-up of 12.0 (IQR: 3.0-16.0) months, and 42.1% (n = 16/38) died over a median follow-up of 12.0 (IQR: 4.0-18.0) months. The most common cause of death was disease progression/recurrence in 81.3% (n = 13/16).

CONCLUSION

Early diagnosis and management of ampullary MANEC is challenging yet crucial to improve outcomes since many patients are diagnosed at an advanced disease stage and have unfavorable outcomes. Multicenter granular data are warranted to further understand and improve outcomes in these patients.

Pancreatic Heterotopia in the Small Bowel: A Case Report and Literature Review

ABSTRACT

Diagnosing pancreatic heterotopia (PH) is challenging, because it is a rare congenital anomaly. We report the case of a 66-year-old man who presented with ileus and jejunal PH diagnosed using single-balloon enteroscopy. Reviewing 178 cases of small intestinal PH in the literature showed that (1) PH mostly occurred at the duodenum (61.8%), followed by the jejunum (22.5%) and ileum (14.6%); (2) patients with ileal PH were younger (mean, 40.7 vs 54.6 years; P < 0.001), while those with jejunal PH were older (mean, 59.5 vs 51.7 years; P = 0.006); (3) most patients with jejunal PH were females, while those with duodenal or ileal PH were predominantly males (M:F = 0.8:1 vs 2.5:1; P = 0.003); (4) asymptomatic cases were rare (15.2% vs 83.4% in small and nonsmall bowel, respectively); (5) most patients with ileal PH presented with bleeding (61.5%), while the remaining had abdominal pain (42.8%); (6) emergent operation was performed in 11 cases (6.2%), mainly at the jejunum (12.5%) and Meckel's diverticulum (25%); and (7) Heinrich's classification may be inconclusive. Enteroscopy was performed in only 6 cases (3.4%), and earlier diagnosis and further minimally invasive procedures could have been achieved with enteroscopy.

Application of electron microscopy in gastroenterology

Electron microscopy has long been used in research in the fields of life sciences and materials sciences. Transmission and scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) analyses have also been performed in the field of gastroenterology. Electron microscopy and EDX enable (1) Observation of ultrastructural differences in esophageal epithelial cells in patients with gastroesophageal reflux and eosinophilic esophagitis; (2) Detection of lanthanum deposition in the stomach and duodenum; (3) Ultrastructural and elemental analyses of enteroliths and bezoars; (4) Detection and characterization of microorganisms in the gastrointestinal tract; (5) Diagnosis of gastrointestinal tumors with neuroendocrine differentiation; and (6) Analysis of gold nanoparticles potentially used in endoscopic photodynamic therapy. This review aims to foster a better understanding of electron microscopy applications by reviewing relevant clinical studies, basic research findings, and the state of current research carried out in gastroenterology science.

Primary extra-pancreatic pancreatic-type acinar cell carcinoma in the right perinephric space: A case report and review of literature

BACKGROUND

Primary extra-pancreatic pancreatic-type acinar cell carcinoma (ACC) is a rare malignancy, and has only been reported in the gastrointestinal tract, liver, and lymph nodes until now. Extra-pancreatic pancreatic-type ACC in the perinephric space has not been reported. Herein, we report the first case of ACC in the perinephric space and describe its clinical and imaging features, which should be considered when differentiating perinephric space neoplasms.

CASE SUMMARY

A 48-year-old man with a 5-year history of hypertension was incidentally found to have an asymptomatic right retroperitoneal mass during a routine health check-up. Laboratory tests were normal. Abdominal computed tomography and magnetic resonance imaging showed an oval hypervascular mass with a central scar and enhanced capsule in the right perinephric space. After surgical resection of the neoplasm, the diagnosis was primary extra-pancreatic pancreatic-type ACC. The patient was alive without recurrence or metastasis during a 15-mo follow-up.

CONCLUSION

This is the first report of an extra-pancreatic ACC in right perinephric space, which should be considered as a possible diagnosis in perinephric tumors.

Title: pancreatic-type mixed acinar neuroendocrine carcinoma of the stomach: a case report and review of the literature

BACKGROUND

The majority of gastrointestinal tumors are adenocarcinomas. Rarely, there are other types of tumors, such as acinar cell carcinoma, and these are often called pancreatic-type acinar cell carcinomas. Among these tumors, some are differentiated into neuroendocrine components. A few of them are MiNENs.

CASE PRESENTATION

The patient was an 80-year-old male who was referred to our hospital for treatment of a pedunculated gastric tumor. It was 5 cm in diameter and detected in the upper gastric body with upper GI endoscopy conducted to investigate anemia. In the biopsy, although hyperplasia of gastric gland cells was noted, no tumor cells were found. Retrospectively, the diagnosis was misdiagnosed. An operation was arranged because bleeding from the tumor was suspected as a cause of anemia and because surgical resection was considered to be desirable for accurate diagnosis. Hence, laparoscopic and endoscopic cooperative surgery was performed. In the pathological examination, several types of epithelial cells that proliferated in the area between the mucosa and deep inside the submucosa were observed. These consisted of acinar-glandular/trabecular patterns and solid. A diagnosis of pancreatic-type acinar cell carcinoma of the stomach with NET G2 and G3 was made based on characteristic cellular findings and the results of immunostaining tests. Each of them consisted of more than 30% of the lesion; a diagnosis of pancreatic-type mixed acinar neuroendocrine carcinoma (pancreatic-type MiNEN) of the stomach or a type of gastric MiNEN was obtained. Anemia was resolved after the operation, and the patient was discharged from the hospital without perioperative complications.

CONCLUSIONS

Pancreatic-type ACC of the stomach that is differentiated into neuroendocrine tumors is very rare. Hence, we report this case along with a literature review.

The clinical profiles, management, and prognostic factors of biliary mixed neuroendocrine nonneuroendocrine neoplasms: A systematic review of the literature

BACKGROUND

Mixed neuroendocrine nonneuroendocrine neoplasms (MiNENs) originating from the biliary system (gallbladder, biliary tract, or ampulla of Vater) are extremely rare and have not been discussed in detail or systematically. We aimed to present the demographics, clinicopathological characteristics, management, and prognostic factors of biliary MiNENs.

METHODS

A systematic search of electronic biomedical databases (Web of Science, PUBMED, and Embase) was performed to identify eligible studies. Survival was analyzed with the Kaplan-Meier method. Log-rank tests were used to evaluate the differences between groups, and the effects of various clinical and histopathological features on prognosis were analyzed by univariate and multivariate Cox regression.

RESULTS

Fifty-three publications (patients, n = 67) were included. The median overall survival time was 21.0 months. Fifty-one patients (76.1%) underwent radical surgery and median survival for 41 months (P < .001). Twenty-two patients who received adjuvant radiochemotherapy treatment after radical surgery had a median survival for 43 months (P = .076). Radical resection (P < .001), Ki-67 index (P = .011), tumor stage (P < .001), neuroendocrine (NEC) grade (P = .011), and non-NEC grade (P = .017) were independent statistically significant prognostic factors according to univariate analysis; radical resection (P = .010) and small morphological subtype (P = .036) were independent statistically significant prognostic factors associated with higher overall survival according to multivariate analysis, and radical resection (P = .005) and age < 65 years (P = .026) were associated with higher recurrence free survival time.

CONCLUSION

Radical resection is essential for long-term survival. Aggressive multimodality therapy with adjuvant radiochemotherapy and biotherapy may improve survival of biliary MiNENs. Further randomized controlled trials are needed to determine the standard treatment.

Cytopathology and ultrastructure identification of primary hepatic acinar cell carcinoma: Case report

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Acinar cell carcinoma originating in the liver proper remains a diagnostic quandary.

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Non-specific imaging features may have led to prior misdiagnosis and poor outcomes.

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Ultrastructural electron microscopy represents a novel tool for identification.

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Heterotopia or metaplastic mechanisms may underlie hepatic acinar cell localization.

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The previous literature is summarized in context of the present case of hepatic ACC.

Introduction

A primary acinar cell carcinoma (ACC) of the liver was incidentally diagnosed in a clinically asymptomatic 80-year-old man. This study aimed to delineate critical diagnostic characteristics of an ACC originating uniquely from the liver to improve its future identification.

Presentation of case

Enhanced MRI revealed a heterogenous, cystic 7.7 × 11.1 × 10.4 cm tumour occupying hepatic segments II and III. The mass demonstrated mild diffuse enhancement in hepatic arterial phase with minimal portal venous washout in a liver without cirrhotic features. A central stellate T2-hyperintense necrotic scar and outer capsule were apparent. No primary lesion or metastasis outside the liver was discernable. Post-left hepatic lobectomy, the tumour immunophenotype was atypical for presumptive diagnoses of hepatocellular carcinoma (HCC) or cholangiocarcinoma. Extensive morphologic workup on electron microscopy definitively diagnosed primary hepatic ACC by establishing presence of secretory zymogen-like granules, intracytoplasmic microvilli and acinar cell differentiation. Cytopathology revealed cellular lumen expressing PAS-positive diastase-resistant granular cytoplasmic contents.

Discussion

This case showcased the novel utility of electron microscopy that was crucial in yielding the definitive diagnosis. The previous literature on hepatic ACC was compiled here in context of the present case. The mechanism of hepatic acinar cell localization was also discussed.

Conclusion

Primary hepatic ACC may easily be confused for other lesions due to nonspecific imaging patterns. Specifically, the presence of a central scar without risk factors for HCC can favour a diagnosis of benign entities such as focal nodular hyperplasia (FNH). Electron microscopy presents an important tool to identify primary hepatic ACC and may improve future patient outcomes.

Mixed Acinar-Endocrine Carcinoma (MAEC) Arising in Duodenal Pancreatic Heterotopia

Mixed acinar-endocrine carcinoma (MAEC) of the pancreas is a rare neoplasm, consisting of at least 25%–30% of acinar and neuroendocrine populations. Patients are often middle-aged and present with nonspecific symptoms. Imaging typically reveals a solid lesion in the pancreatic head. Management involves surgical resection and the overall prognosis is variable. Here, we present a case of a 48-year-old male who presented with a MAEC arising from duodenal pancreatic heterotopia. This is the one of the first cases, with histologic evidence, of MAEC arising from pancreatic heterotopia.

Malignant Transformation of Ectopic Pancreas

Malignant transformation of ectopic pancreas tissue is a diagnostic challenge as clinical symptoms and radiographic features of these tumors are non-specific. Given the rarity of these lesions, it is usually neither suspected nor included in the diagnostic workup of different tumors. We conducted a comprehensive literature review regarding malignancy arising from ectopic pancreas for a better understanding of its frequency, clinicopathological features, and prognosis. A literature search was performed in three major databases: PubMed, Cochrane, and Web of Science. Fifty-four well-documented cases of malignant ectopic pancreas were identified in the published literature. Our analysis provided the following observations: (1) there was a slight predominance of males over females; (2) most patients with malignant transformation of ectopic pancreas were middle-aged; (3) most commonly, the tumor was located in the stomach; (4) most tumors were adenocarcinomas; (5) most frequently, the malignancy arose within a type I heterotopia according to Heinrich classification; (6) macroscopically, a subepithelial-like appearance was most frequently observed; and (7) improved prognosis for ectopic pancreatic malignancies in comparison with reported survival data for orthotopic pancreatic cancer. Even if the majority of cases of ectopic pancreas are incidental findings and malignant transformation is a rare event, pancreatic heterotopy should be considered as a source of potentially malignant lesions.

Pancreatic mixed acinar-neuroendocrine carcinoma, a unique diagnostic challenge on FNA cytology: A small series of two cases with literature review

Mixed acinar-neuroendocrine carcinoma (MANEC) of the pancreas is a rare tumor. We present two cases of MANEC diagnosed on endoscopic ultrasound (EUS) guided fine-needle aspiration (FNA). The first patient is a 33-year-old male who had a 3.6 cm mass in the uncinate process and liver metastasis. The second patient is a 66-year-old male with a 10 cm mass in the pancreatic tail. The FNA smears from both cases were hypercellular with neoplastic cells in loosely cohesive clusters and many naked nuclei. In both cases, the tumor cells were positive for CKAE1/3, synaptophysin, chromogranin, and trypsin by immunohistochemistry. Final diagnoses of MANEC were rendered based on cytological features and immunohistochemical profiles. To date, 44 cases of MANEC have been reported in the English literature, only three of which were diagnosed on cytopathology specimens before surgical resection. Our report adds two more cases diagnosed on cytopathology alone. Herein, we discuss the various cytomorphologic and clinical features of MANEC and present a brief review of the literature. Diagn. Cytopathol.

Case report: primary acinar cell carcinoma of the liver treated with multimodality therapy

We describe a case of primary acinar cell carcinoma (ACC) originating in the liver in a 54-year-old female, diagnosed following persistent abnormal elevated liver function. Imaging revealed two masses, one dominant lesion in the right hepatic lobe and another in segment IVA. A right hepatectomy was performed to remove the larger lesion, while the mass in segment IVA was unresectable due to its proximity to the left hepatic vein. Immunohistochemical staining showed positivity for trypsin and chymotrypsin. Postoperatively the patient underwent hepatic arterial embolization of the other unresectable lesion followed by FOLFOX chemotherapy. At 20 months from diagnosis the patient is currently under observation with a decreasing necrotic mass and no other disease evident. Based on histology, immunohistochemistry and radiological findings a diagnosis of primary ACC of the liver was made. Genomic assessment of somatic mutations within the patient's tumor was also performed through next generation sequencing and findings were consistent with an acinar malignancy. This case highlights a rare tumor subtype treated with a combination of therapeutic modalities through a multidisciplinary approach.

Heterotopic Pancreas of the Gastrointestinal Tract and Associated Precursor and Cancerous Lesions: Systematic Pathologic Studies of 165 Cases

Heterotopic pancreas (HP) can be detected by accompanying symptoms or incidentally during gastrointestinal (GI) tract tumor resection. We compared clinicopathologic features among 165 resected HPs (57 gastric [35%], 56 duodenal [34%], 30 omental [18%], and 22 jejunal [13%]). Symptomatic HPs (79/135 GI tract wall HPs, 59%) were larger (P=0.05), more common in younger patients and in a gastric location (both P<0.001), and more frequently associated with lymphoid cuffs (P=0.03) than incidentally found HPs. Gastric/jejunal HPs were more frequently symptomatic (P<0.001), deeply located (P=0.03), and associated with lymphoid cuffs (P=0.008) and pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasms (PanIN/IPMN; P=0.001) than duodenal HPs. HP was frequently associated with acinar-ductal metaplasias (117/135 GI tract wall HPs, 87%) and PanINs/IPMNs (68/135, 50%); those with PanINs/IPMNs were larger (P<0.001), more frequently located in stomach (P=0.001), had deeper wall involvement (P=0.03), and more often showed infiltrative growth (P<0.001) and lymphoid cuffs (P=0.02). Four HPs containing PanINs abutted adenocarcinomas, all expressing wild-type KRAS and intact SMAD4/DPC4 expression. Thus, symptomatic HP is associated with younger age, larger size, gastric location, and lymphoid cuffs. HPs containing PanINs/IPMNs (usually low grade) are larger and more common in stomach, have deeper wall location, and show infiltrative growth and lymphoid cuffs. Adenocarcinomas are rarely observed adjacent to HPs with PanINs/IPMNs. KRAS mutational and SMAD4/DPC4 immunohistochemical studies can discriminate between adenocarcinoma derived from HP and concurrent adenocarcinoma with HP.

Ampullary Mixed Adenoneuroendocrine Carcinoma: Surprise Histology, Familiar Management

INTRODUCTION

Mixed adenoneuroendocrine carcinoma (MANEC) has recently been defined by the World Health Organization in 2010. These are rare tumors and MANECs of ampullary region are even rarer. Only 19 cases have been reported in literature. We present 3 cases; the largest series, second case of amphicrine tumor and first case associated with chronic pancreatitis.

METHODS

Retrospective review of 3 patients who were diagnosed to have ampullary MANEC.

RESULTS

All 3 patients were diagnosed preoperatively as neuroendocrine carcinoma and underwent margin negative pancreaticoduodenectomy. The histopathology revealed MANECs of small cell, mixed type in 2 patients and large cell, amphicrine type in 1 patient. The neuroendocrine component was grade 3 in all, the tumor was T3 in 2 and T2 in 1 and all had nodal metastases. Two patients received adjuvant chemotherapy and 2 of them had recurrence at 13 and 16 months. The median survival was 15 months.

CONCLUSION

Ampullary MANECs are rare tumors. They are diagnosed on histopathologic examination of the resected specimen. Clinical presentation, management, and prognosis is similar to ampullary adenocarcinoma in literature.

Mixed adenoneuroendocrine carcinoma of the ampulla of Vater: A case report

Mixed adenoneuroendocrine carcinomas (MANECs) are rare biphasic tumour types, which are morphologically recognisable as both gland-forming and neuroendocrine neoplasms. Within the gastrointestinal tract, MANECs occur predominantly in the stomach or colorectum. The present study described a case of a MANEC originating from the ampullary region. The patient presented with widespread metastatic disease. Biopsy samples obtained from the ampullary primary tumour disclosed a complex lesion with adenocarcinoma and neuroendocrine small cell carcinoma components, positive for the intestinal transcription factor caudal type homeobox-2 and for neuroendocrine markers, including chromogranin A, synaptophysin, cluster of differentiation 56/neural cell adhesion molecule. By contrast, biopsy samples obtained from metastatic tissue revealed pure neuroendocrine carcinoma. As exemplified by this true mixed tumour, tumour heterogeneity evolves as the major challenge in oncology today, with potentially severe implications for the choice of chemotherapy. The assessment of metastatic sites may render valuable diagnostic information that is crucial for clinical decision-making and patient management.

Cytological features of mixed adenoneuroendocrine carcinoma of the ampulla: two case reports with review of literature

Mixed adenoneuroendocrine carcinoma (MANEC) of ampulla is rare, with only 13 cases reported, and the diagnoses were all based on histology mostly after surgery. We describe two new cases with cytological features of signet ring-cell carcinoma mixed with small-cell carcinoma, and intestinal adenocarcinoma mixed with large-cell neuroendocrine carcinoma. Our cases and literature review demonstrate the higher frequency of periampullary-duodenum subtype in MANEC compared with non-MANEC ampullary carcinomas. In accordance, of the 14 MANEC cases with detailed morphology available, the most common glandular components are intestinal-type carcinoma (6/14), followed by goblet carcinoid tumor (3/14), signet ring-cell carcinoma (2/14), pancreatobiliary-type carcinoma (2/14), and pancreatic acinar cell carcinoma (1/14). The intestinal-type carcinoma and goblet carcinoid in MANEC are favorable histological types showing no distant metastasis or mortality (0/9) during 6-36 months follow-up. In contrast, the signet ring cell, pancreatobiliary-type carcinoma, and acinar cell carcinoma are unfavorable with distant metastatic rate and mortality rate of 80% (4/5) during 3-16 months follow-up. The combination of favorable glandular histological types with high-grade neuroendocrine tumors (neuroendocrine carcinoma) has a mortality rate of 0% (0/3), whereas the combination of unfavorable glandular types with low-grade neuroendocrine tumors (e.g., carcinoid, atypical carcinoid) has a mortality rate of 100% (3/3). In addition, younger age (<40 years) seems to be associated with high mortality rate of 100% (2/2). Overall, cytology preparations are able to make the diagnosis of MANEC and distinguish the subcomponents. Disease progression is apparently driven by the carcinomatous component of the tumor.

Collision tumor of the ampulla of Vater - Coexistence of neuroendocrine carcinoma and adenocarcinoma: report of a case

Herein, we present a case of coexisting neuroendocrine carcinoma and conventional adenocarcinoma (collision tumor) in the ampulla of Vater, which has seldom been reported in the literature. A 51-year-old man presented with a month history of jaundice. MRCP disclosed about 1.9×1.8 cm sized heterogeneously enhancing mass in ampulla of Vater, causing obstructions of distal common bile duct. He underwent pylorus-preserving pancreaticoduodenectomy under the diagnosis on ampulla of Vater cancer. Pathologically, sections on the ampulla of Vater showed conventional ductal adenocarcinoma extended and collided with poorly differentiated neuroendocrine carcinoma. In conclusion, we hereby presented a case of coexisting neuroendocrine carcinoma and conventional adenocarcinoma in the ampulla of Vater.

The prevalence of pancreatic acinar differentiation in gastric adenocarcinoma: report of a case and immunohistochemical study of 111 additional cases

Although pancreatic acinar metaplasia in the gastric mucosa is well recognized in chronic gastritis, gastric carcinoma with acinar differentiation is very rare. We encountered a case of gastric adenocarcinoma with prominent histologic and immunohistochemical features of pancreatic acinar differentiation in the absence of identifiable heterotopic pancreatic tissue. Distinct glandular and diffuse patterns of adenocarcinoma were also present, and there was focal mucin production. The tumor strongly expressed pancreatic exocrine enzymes trypsin and chymotrypsin, and focal neuroendocrine staining was also present. To investigate the prevalence of acinar differentiation in histologically typical gastric cancers, we performed immunohistochemical staining for trypsin and chymotrypsin on a tissue microarray containing 111 conventional gastric adenocarcinomas (60 intestinal, 28 mixed, 22 diffuse type, and 1 undifferentiated). No obvious morphologic evidence of acinar differentiation was identified in any of the 111 cases. Although some cases showed equivocal staining for at least 1 pancreatic exocrine enzyme on the initial tissue microarray sections, repeat immunohistochemical staining on representative whole-tissue sections failed to reproduce positive staining. Thus, acinar differentiation is rare in gastric adenocarcinomas, other than in histologically unusual cases such as the one we report, and in others from the literature, which are reviewed.

Mixed Adenoneuroendocrine Carcinomas (MANECs) of the Gastrointestinal Tract: An Update

The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.

Acinar cell carcinoma: a possible diagnosis in patients without intrapancreatic tumour

BACKGROUND

Acinar cell carcinomas of the pancreas are rare neoplasms. Usually diagnosed at an advanced stage, in general they are large solid pancreatic tumours with an average size of more than 10 cm.

AIMS AND RESULTS

We report 3 cases of acinar cell carcinomas involving the peripancreatic lymph nodes, the liver hilum and the colon respectively, without clinical or pathological evidence of pancreatic tumours. These highly cellular neoplasms showed a predominantly acinar cell differentiation intermingled with a ductal component, with intracellular or extracellular mucin production by at least 25% of tumour cells. In addition, one case showed endocrine differentiation. Diffuse immunoreactivity for acinar enzymes trypsin and chymotrypsin was present in all cases.

CONCLUSION

The occurrence of acinar cell carcinomas outside the pancreas underlines the notion that acinar cell carcinomas may originate in extrapancreatic sites and probably develop from heterotopic or metaplastic pancreatic foci present along the biliary tract.

Peri-ampullary mixed acinar-endocrine carcinoma

Mixed acinar-endocrine carcinomas (MAEC) are rare tumors of the pancreas. We present the case of a patient with periampullary tumor that presented with painless jaundice and after investigation was found to have MAEC. He underwent pancreaticoduo-dunectomy with tumor free margins and negative lymph nodes. The patient presented with local recurrence and liver metastasis after 1 year and is on chemotherapy with stable lesions 30 months after the diagnosis.

Invasive ductal adenocarcinoma arising from pancreatic heterotopia in rectum: case report and review of literature

Pancreatic heterotopia has been described at several abdominal and intrathoracic locations, most commonly in the stomach and upper part of the small intestine. Its occurrence in the rectum is unusual, and malignant transformation in the rectum has not been reported. We report a case of ductal adenocarcinoma arising in a rectal pancreatic heterotopia in a 42-year-old woman with delayed local recurrence. The tumor was composed of well to moderately differentiated ductal adenocarcinoma infiltrating through the full thickness of the anorectal wall with extension into the vaginal septum. A focus of ectopic pancreas consisting of exocrine acini and small ducts adjacent to the tumor with some ducts showing mild to severe dysplasia reminiscent of pancreatic intraepithelial neoplasia was also observed. Although our literature search found 31 documented reports of tumors arising in the heterotopic pancreas, the present case is the first case of ductal adenocarcinoma arising in a focus of pancreatic heterotopia in the rectum.

Primary acinar cell carcinoma of the liver

We report a case of acinar cell carcinoma primary to the liver. The tumor was diagnosed in a 35-year-old woman complaining of abdominal pain and asthenia; serum alpha-fetoprotein (AFP) levels were increased at 6,000 IU/mL; imaging studies showed a hypervascular mass located in the left lobe of the liver. A left lobectomy was performed. The tumor had a heterogeneous appearance. In well-differentiated areas, tumor cells formed acinar structures, had a pyramidal shape and a highly eosinophilic, granular cytoplasm, PAS diastase resistant. In less-differentiated areas, tumor cells were endocrinelike. The immunohistochemical study showed that tumor cells expressed trypsin. Alpha-fetoprotein and alphal-antritrypsin were detected in about 30% of cells; HepPar1 was present in 15% of cells. Chromogranin A and synaptophysin were detected in rare cells. After surgery, serum AFP levels quickly returned to normal; no evidence of recurrence or metastasis was observed during follow-up. The final diagnosis, based on histological, immunohistochemical, and ultrastructural arguments, was extra-pancreatic acinar cell carcinoma, primary to the liver. This unusual lesion is likely to be the result of an abnormal differentiation pathway involving a transformed multipotential progenitor cell.

Primary acinar cell carcinoma of the ampulla of Vater

Acinar cell carcinoma of the pancreatobiliary system is a relatively rare malignant neoplasm arising usually in the pancreatic parenchyma. We experienced a 68-year-old woman who presented with obstructive jaundice due to an ampullary mass 1.0 cm in diameter, detected by abdominal computed tomography and endoscopic examination. The patient underwent a curative surgical operation, and histopathological examination revealed that the tumor was confined to the ampulla of Vater with no continuity to the pancreatic parenchyma. The tumor cells showed acinar or tubular arrangement with eosinophilic to basophilic granular cytoplasm, findings identical to those of acinar cell carcinoma of the pancreas. Immunohistochemically, the tumor cells were positive for lipase. From these findings, we concluded that the tumor was primary acinar cell carcinoma arising in the ampulla of Vater, probably originating from heterotopic pancreatic tissue. This is the first reported case of primary acinar cell carcinoma in the ampulla of Vater.

[Mixed endocrine tumors]

Mixed endocrine tumors are tumors composed of at least two distinct tumor populations, one of which is endocrine. Because of their rarity and unusual presentation, endocrine mixed tumors raise many problems of diagnosis, management and therapy. Three main types of endocrine mixed tumors are recognized: The existence of these various types has been confirmed by recent molecular studies, even if the same studies have also shown that the histogenesis of a mixed endocrine tumor cannot be predicted from its histological features. Composite tumors are the less rare mixed tumors. The recent WHO classification recommends to restrict the term of composite endocrine tumor to the epithelial tumors containing at least 30% of obviously tumoral endocrine cells; some authors recommend to use higher thresholds, of at least 50%, in order to avoid overdiagnosis. The endocrine component is usually well differentiated, easily identified by its suggestive histological features; the endocrine nature of tumor cells is confirmed by the immunodetection of specific endocrine and neuro-endocrine markers (such as chromogranin A and synaptophysin). In some cases, the endocrine component is poorly differentiated: the demonstration of neuro-endocrine markers is necessary to confirm the diagnosis. Mixed tumors can occur in every anatomical site; they are more frequent in organs containing endocrine cells in the normal state (especially the digestive tract and the pancreas), but they can also be observed in organs devoid of endocrine cells (such as the mammary gland). The management of mixed endocrine tumors must take into account the more aggressive component. Mixed tumors containing a well differentiated endocrine component and an adenocarcinomatous component are to be treated like adenocarcinomas. Mixed tumors containing a poorly differentiated endocrine component must be considered as poorly differentiated endocrine carcinomas.

Ampullary pancreatoblastoma in an elderly patient: a case report and review of the literature

Pancreatoblastoma, generally regarded as a pediatric malignant tumor, is rarely found in the adult population. Only 13 adults with pancreatoblastoma, ranging in age from 19 to 68 years, have previously been reported in the world literature. A diagnosis of pancreatoblastoma relies on characteristic histologic features, including epithelial differentiation and, more importantly, squamoid differentiation. Despite aggressive therapy, adults with pancreatoblastoma have a poor outcome. We describe a 78-year-old woman who presented with painless jaundice and was found on abdominal computed tomographic scan to have a 2.7-cm ampullary mass. The patient underwent successful pancreaticoduodenectomy. Pathologic examination of the resected tumor revealed findings characteristic of pancreatoblastoma. The tumor formed acinar and glandular structures, solid areas, and contained many "squamoid corpuscles," a defining feature of pancreatoblastoma. The tumor cells also showed acinar and ductal phenotype by immunohistochemistry. To the best of our knowledge, this case represents the oldest patient with pancreatoblastoma to be described in the literature to date and the first to occur in the ampulla of Vater. We review previously published cases and discuss the clinical and histopathologic features of adult pancreatoblastoma.