Prevalence and prognostic significance of acinar cell differentiation in pancreatic endocrine tumors

Comprehensive review of pancreatic acinar cell carcinoma: epidemiology, diagnosis, molecular features and treatment

Pancreatic acinar cell carcinoma is a rare form (0.2-4.3%) of pancreatic neoplasm with unique clinical and molecular characteristics, which largely differ from pancreatic ductal adenocarcinoma. Pancreatic acinar cell carcinoma occurs more frequently in males and can occur in children. Serum lipase is elevated in 24-58% of patients with pancreatic acinar cell carcinoma. Pancreatic acinar cell carcinomas tend to be large at diagnosis (median tumour size: ~5 cm) and are frequently located in the pancreas head. Radiologically, pancreatic acinar cell carcinoma generally exhibits a solid appearance; however, necrosis, cystic changes and intratumoral haemorrhage can occur in larger lesions. Immunostaining is essential for the definitive diagnosis of pancreatic acinar cell carcinoma. Compared with pancreatic ductal adenocarcinoma, pancreatic acinar cell carcinoma has a more favourable prognosis. Although radical surgery is recommended for patients with pancreatic acinar cell carcinoma who do not have distant metastases, the recurrence rate is high. The effectiveness of adjuvant therapy for pancreatic acinar cell carcinoma is unclear. The response to FOLFIRINOX is generally favourable, and some patients achieve a complete response. Pancreatic acinar cell carcinoma has a different genomic profile compared with pancreatic ductal adenocarcinoma. Although genomic analyses have shown that pancreatic acinar cell carcinoma rarely has KRAS, TP53 and CDKN2A mutations, it has a higher prevalence of homologous recombination-related genes, including BRCA1/2 and ATM, than pancreatic ductal adenocarcinoma, suggesting high sensitivity to platinum-containing regimens and PARP inhibitors. Targeted therapies for genomic alternations are beneficial. Therefore, genetic testing is important for patients with pancreatic acinar cell carcinoma to choose the optimal therapeutic strategy.

Integrated Genomic and Clinicopathologic Approach Distinguishes Pancreatic Grade 3 Neuroendocrine Tumor From Neuroendocrine Carcinoma and Identifies a Subset With Molecular Overlap

Distinguishing grade 3 pancreatic neuroendocrine tumor (G3 PanNET) from neuroendocrine carcinoma (PanNEC) is a known diagnostic challenge, and accurate classification is critical because clinical behavior and therapies differ. Although current recommendations suggest that immunohistochemistry for p53, Rb, ATRX, and DAXX can distinguish most cases, some cases remain difficult to classify using this approach. In this study, we reviewed 47 high-grade neoplasms originally diagnosed as pancreatic neuroendocrine neoplasms. In addition to the currently recommended stains, we performed capture-based sequencing of approximately 500 cancer genes and immunohistochemistry for p16 and trypsin or chymotrypsin. Using an integrated molecular and clinicopathologic approach, 42 (89%) of 47 cases had a clear final diagnosis of either G3 PanNET (n = 17), PanNEC (n = 17), or mixed acinar-NEC (n = 8). The 17 G3 PanNETs demonstrated frequent alterations in MEN1 (71%), DAXX (47%), ATRX (24%), TSC2 (35%), SETD2 (42%), and CDKN2A (41%). Contrary to prior reports, TP53 alterations were also common in G3 PanNETs (35%) but were always mutually exclusive with CDKN2A alterations in this group. The 17 PanNECs demonstrated frequent alterations in TP53 (88%), cell cycle genes RB1 (47%), CCNE1/CCND1 (12%), CDKN2A (29%), and in KRAS (53%) and SMAD4 (41%); TP53 was coaltered with a cell cycle gene in 76% of PanNECs. Diffuse strong p16 staining was observed in 69% of PanNECs in contrast to 0% of G3 PanNETs. The 8 acinar-NECs had recurrent alterations in ATM (25%), APC (25%), and STK11 (25%). Five cases remained difficult to classify, 3 of which exhibited overlapping molecular features with alterations in MEN1 with or without ATRX, and RB1 with or without TP53, making it unclear whether to classify as PanNET or PanNEC. Our data demonstrate that molecular profiling and immunohistochemistry for p16 greatly improve the diagnostic accuracy of high-grade pancreatic neuroendocrine neoplasms and identify a subset of rare cases with overlapping features of both PanNET and PanNEC.

Pancreatic acinar cell carcinoma: A comprehensive review

Acinar cell carcinoma (ACC) is a rare pancreatic malignancy with distinctive clinical, molecular, and morphological features. The long-term survival of ACC patients is substantially superior to that of pancreatic adenocarcinoma patients. As there are no significant patient series about ACCs, our understanding of this illness is mainly based on case reports and limited patient series. Surgical resection is the treatment of choice for patients with the disease restricted to one organ; however, with recent breakthroughs in precision medicine, medicines targeting the one-of-a-kind molecular profile of ACC are on the horizon. There are no standard treatment protocols available for people in which a total surgical resection to cure the condition is not possible. As a result of shared genetic alterations, ACCs are chemosensitive to agents with activity against pancreatic adenocarcinomas and colorectal carcinomas. The role of neoadjuvant or adjuvant chemoradiotherapy has not been established. This article aims to do a comprehensive literature study and present the most recent information on acinar cell cancer.

Bcl-10, trypsin and synaptophysin helps recognize acinar cell and mixed acinar neuroendocrine cell carcinoma of the pancreas on both preoperative cytological samples and needle biopsy specimens

OBJECTIVE

Acinar cell carcinoma (ACC) of the pancreas are known to be rare and difficult to be recognize because they mimic other unrelated tumors (neuroendocrine, solid pseudopapillary) with different clinical behavior. Especially in the setting of inoperable patients, fine needle aspiration cytology (FNAC), core needle biopsy (FNAB) and immunocyto/histochemistry (ICC/IHC) play a crucial role in the differential diagnosis. The biological material available for ICC tests obtained by minimal invasive procedures is usually limited. Aim of the current study was to evaluate diagnostic panel based on a limited number of ICC markers for typing preoperatively ACC of the pancreas.

METHODS

Of 1820 needle sampling procedures performed and related to pancreatic lesions, 21 cases were extracted with a confirmed diagnosis of ACC on histology. Of them,12 were pure ACC and 9 mixed acinar-neuroendocrine carcinoma (MANEC). Smears of ACC, MANEC and a control group composed of 34neuroendocrine, 7solid pseudopapillary, 50ductal and 4 adenosquamous carcinoma were assessed with an ICC panel made up of BCL10, trypsin, synaptophysin, chromograninA, β-catenin.

RESULTS

On cytology, BCL10 sensitivity and specificity for ACC was 100%. Trypsin correctly recognized 90% of the cases. Synaptophysin was helpful to correctly identify all the cases with a mixed neuroendocrine component. No significant cross-reaction was observed between BCL10 and trypsin in any of the control group case.

CONCLUSIONS

BCL10 is a determinant marker for the diagnosis of acinar cell carcinoma and mixed acinar neuroendocrine cell carcinoma of the pancreas in a pre-operative citologic/histologic setting.

CD57 (Leu-7, HNK-1) immunoreactivity seen in thin arteries in the human fetal lung

CD57 (synonyms: Leu-7, HNK-1) is a well-known marker of nerve elements including the conductive system of the heart, as well as natural killer cells. In lung specimens from 12 human fetuses at 10-34 weeks of gestation, we have found incidentally that segmental, subsegmental, and more peripheral arteries strongly expressed CD57. Capillaries near developing alveoli were often or sometimes positive. The CD57-positive tissue elements within intrapulmonary arteries seemed to be the endothelium, internal elastic lamina, and smooth muscle layer, which corresponded to tissue positive for a DAKO antibody reactive with smooth muscle actin we used. However, the lobar artery and pulmonary arterial trunk as well as bronchial arteries were negative. Likewise, arteries in and along any abdominal viscera, as well as the heart, thymus, and thyroid, did not express CD57. Thus, the lung-specific CD57 reactivity was not connected with either of an endodermal- or a branchial arch-origin. CD57 antigen is a sugar chain characterized by a sulfated glucuronic acid residue that is likely to exist in some glycosphingolipids. Therefore, a chemical affinity or an interaction might exist between CD57-positive arterioles and glycosphingolipids originating from alveoli, resulting in acceleration of capillary budding to make contact with the alveolar wall. CD57 might therefore be a functional marker of the developing air-blood interface that characterizes the fetal lung at the canalicular stage.

Prkar1a gene knockout in the pancreas leads to neuroendocrine tumorigenesis

Carney complex (CNC) is a rare disease associated with multiple neoplasias, including a predisposition to pancreatic tumors; it is caused most frequently by the inactivation of the PRKAR1A gene, a regulator of the cyclic AMP (cAMP)-dependent kinase (PKA). The method used was to create null alleles of prkar1a in mouse cells expressing pdx1 (Δ-Prkar1a). We found that these mice developed endocrine or mixed endocrine/acinar cell carcinomas with 100% penetrance by the age of 4-5 months. Malignant behavior of the tumors was seen as evidenced by stromal invasion and metastasis to locoregional lymph nodes. Histologically, most tumors exhibited an organoid pattern as seen in the islet-cell tumors. Biochemically, the lesions exhibited high PKA activity, as one would expect from deleting prkar1a The primary neuroendocrine nature of these tumor cells was confirmed by immunohistochemical staining and electron microscopy, the latter revealing the characteristic granules. Although the Δ-Prkar1a mice developed hypoglycemia after overnight fasting, insulin and glucagon levels in the plasma were normal. Negative immunohistochemical staining for the most commonly produced peptides (insulin, c-peptide, glucagon, gastrin and somatostatin) suggested that these tumors were non-functioning. We hypothesize that the recently identified multipotent pdx1+/insulin- cell in adult pancreas, gives rise to endocrine or mixed endocrine/acinar pancreatic malignancies with complete prkar1a deficiency. In conclusion, this mouse model supports the role of prkar1a as a tumor suppressor gene in the pancreas and points to the PKA pathway as a possible therapeutic target for these lesions.

Metastatic pancreatic acinar cell carcinoma in a younger male with marked AFP production: A potential pitfall on fine needle aspiration biopsy

A 30-year-old male presented to his doctor with complaints of abdominal pain and was found to have retroperitoneal as well as multiple hepatic masses. A serum alpha-fetoprotein (AFP) level was significantly elevated (17,373 ng mL^-1 ), raising suspicions for a metastatic germ cell tumor. Fine needle aspiration biopsy of the pancreatic lesion revealed atypical epithelioid cells with round nuclei, large prominent nucleoli, and granular cytoplasm. The morphologic differential diagnosis included pancreatic neoplasm, metastatic germ cell tumor, other metastatic carcinoma, and melanoma. An extensive panel of immunohistochemical stains confirmed the diagnosis of acinar cell carcinoma. The diagnosis of acinar cell carcinoma could be confounded by the markedly increased AFP level, particularly in the setting of a retroperitoneal mass in a younger male. The increased AFP level in the setting of an acinar cell tumor is a potential pitfall to correct diagnosis by cytology. As the treatment for these two entities differs considerably, acute awareness of the phenomenon is important. We present a case of pancreatic ACC with an increased AFP level diagnosed on a cytology specimen. Diagn. Cytopathol. 2017;45:133-136. © 2016 Wiley Periodicals, Inc.

Mixed acinar-endocrine carcinoma of pancreas: A case report and brief review of the literature

Mixed acinar-endocrine carcinoma (MAEC) of the pancreas is a rare entity. We present a 65-year-old Chinese female who was admitted with jaundice and nagging epigastric pain with intermittent diarrhea for 1 month. She eventually underwent abdominal magnetic resonance imaging, which showed an 8×6 cm mass in the head of the pancreas and showed two abnormal lesions in the liver simultaneously. MAEC of the pancreas with synchronous hepatic metastasis was confirmed with immunohistochemistry after Whipple operation and hepatic partial resection of the lesions. Postoperative recovery of this patient was uneventful, and no evidence of recurrence or metastasis was observed after 12 months of follow-up. MAEC of pancreas is thought to be extremely rare and lack of typical clinical symptoms. The prognosis is poor overall, but early detection with complete resection may be beneficial to patients.

Transcriptomic analysis predicts survival and sensitivity to anticancer drugs of patients with a pancreatic adenocarcinoma

A major impediment to the effective treatment of patients with pancreatic ductal adenocarcinoma (PDAC) is the molecular heterogeneity of this disease, which is reflected in an equally diverse pattern of clinical outcome and in responses to therapies. We developed an efficient strategy in which PDAC samples from 17 consecutive patients were collected by endoscopic ultrasound-guided fine-needle aspiration or surgery and were preserved as breathing tumors by xenografting and as a primary culture of epithelial cells. Transcriptomic analysis was performed from breathing tumors by an Affymetrix approach. We observed significant heterogeneity in the RNA expression profile of tumors. However, the bioinformatic analysis of these data was able to discriminate between patients with long- and short-term survival corresponding to patients with moderately or poorly differentiated PDAC tumors, respectively. Primary culture of cells allowed us to analyze their relative sensitivity to anticancer drugs in vitro using a chemogram, similar to the antibiogram for microorganisms, establishing an individual profile of drug sensitivity. As expected, the response was patient dependent. We also found that transcriptomic analysis predicts the sensitivity of cells to the five anticancer drugs most frequently used to treat patients with PDAC. In conclusion, using this approach, we found that transcriptomic analysis could predict the sensitivity to anticancer drugs and the clinical outcome of patients with PDAC.

Report of a case of acinar cell carcinoma with its differential diagnosis on endoscopic ultrasound-guided fine-needle aspiration cytology

Acinar cell carcinomas (ACCs) of the pancreas are a rare tumor accounting for only about 2% of all pancreas tumors. We report herein on this case and discuss how to distinguish ACCs from neuroendocrine tumors (NETs) and solid pseudo-papillary tumor (SPTs) morphologically and immunohistochemically. In cytological findings, the nuclear-cytoplasmic ratio was high, and the cytoplasm was granular, but zymogen granules were not evident. The nucleus was biased in location, assuming small circular and irregular forms. Chromatin was fine granular in shape and distributed nonuniformly, accompanied by evident nucleoli. Immunohistochemically was positive for β-catenin (cell membrane and part of nuclei), synaptophysin (focal), chromogranin A (focal) and chymotrypsin were all positive. Although the cytological distinction of ACCs from NETs and SPTs is difficult, the nuclear chromatin pattern and nuclear inclusion bodies, pseudopapillary arrangement and hyaline globules seem to play an important role in the cytological differential diagnosis. Furthermore, not only enzymatic and neuroendocrine markers, but also antibodies to β-catenin, vimentin and so on seem to be useful in the differential diagnosis.

Clinical characteristics of adenosquamous carcinoma of the pancreas: a matched case-control study

OBJECTIVES

Adenosquamous carcinoma of the pancreas (ASC) is a variant of pancreatic ductal adenocarcinoma (PDAC), but the prognosis remains unclear. The purpose of this study was to clarify the prognosis of ASC using a matched case-control design.

METHODS

We evaluated clinical characteristics of ASC treated between 2001 and 2011 in our institution. As controls, PDAC cases matched with ASC cases for sex, age, pretreatment Eastern Cooperative Oncology Group performance status, location, initial therapy and American Joint Committee on Cancer TNM staging for pancreatic cancer were also evaluated.

RESULTS

Of the 914 cases of pancreatic neoplasm, 28 cases (3.06%) of ASC were identified, and 56 cases of PDAC were matched as controls. Median overall survival (OS) was significantly worse for ASC (8.38 months) than for PDAC (15.75 months; hazard ratio [HR], 1.94; 95% confidence interval, 1.07-3.51; P = 0.026). Of the 22 unresected cases, median OS was again significantly worse for ASC (4.67 months) than for PDAC (12.36 months; HR, 2.39; 95% confidence interval, 1.27-4.51; P = 0.007).

CONCLUSION

These results demonstrate that ASC is more aggressive than PDAC.

Mixed acinar-endocrine carcinoma of the pancreas: new clinical and pathological features in a contemporary series

OBJECTIVE

The objective of this study was to characterize the novel clinical and pathological features of mixed acinar-endocrine carcinoma of the pancreas.

METHODS

This was a retrospective review of medical records and surgical pathology specimens of patients with a diagnosis of mixed acinar-endocrine carcinoma of the pancreas at Cedars-Sinai Medical Center between 2005 and 2011. Additional immunohistochemistry was performed on the specimens of some patients.

RESULTS

Five patients were identified. The median age at presentation was 74 years (range, 59-89 years), and all patients were male. The presenting symptoms were all related to tumor mass effects. The median size of the tumor was 10 cm (range, 3.9-16 cm). Preoperative clinical diagnosis aided by fine-needle aspiration biopsy was incorrect in all 5 cases. Most tumors (3/5) exhibited predominantly endocrine differentiation without hormonal production. Only 10% to 30% of cells were truly amphicrine, whereas most were differentiated into either endocrine or acinar phenotype. The clinical behavior ranged from moderate to aggressive with postoperative survival from 2.5 months to more than 3 years. Four patients received neoadjuvant or adjuvant chemotherapy with variable responses.

CONCLUSIONS

Mixed acinar-endocrine carcinoma of the pancreas appears to be not uncommon in men, may harbor predominantly endocrine component, is often misdiagnosed by cytology, and exhibits variable clinical behavior. Mixed acinar-endocrine carcinoma of the pancreas should be considered in older patients with sizable pancreatic mass and may warrant aggressive surgical resection and chemotherapy.

Cytomorphologic and immunophenotypical features of acinar cell neoplasms of the pancreas

BACKGROUND

Acinar cell neoplasms of the pancreas are rare but when encountered, the diagnosis is often established based on cytology specimens. Diagnostic accuracy is important because acinar cell carcinomas are aggressive yet may mimic tumors with different outcomes and management.

METHODS

The authors identified all patients with a diagnosis of acinar cell neoplasm in the institutional database; assessed cytomorphology and immunocytochemistry for trypsin, chymotrypsin, synaptophysin, chromogranin A, and MIB-1; and compared all cytology and final histological diagnoses for diagnostic discrepancies.

RESULTS

Cytological features were described for 16 histologically proven malignant acinar cell neoplasms: acinar cell carcinoma (8 cases), mixed acinar-neuroendocrine carcinoma (6 cases), mixed acinar-ductal carcinoma (1 case), and pancreatoblastoma (1 case).The majority of aspirates from acinar cell cystadenomas were nondiagnostic or negative (5 of 6 cases; 83%). Acinar and neuroendocrine differentiation that was detected by immunocytochemistry in >20% of tumor cells was found to be correlated with mixed acinar-neuroendocrine carcinoma histology. Cytohistological correlation included 32 patients with 17 discordant diagnoses (53%). The following preoperative cytology diagnoses proved to be acinar cell neoplasms on resection: neuroendocrine tumor (5 cases), adenocarcinoma (5 cases), atypical ductal cells (2 cases), solid pseudopapillary neoplasm, and hepatocellular carcinoma. Three aspirates diagnosed as acinar cell carcinoma by cytology proved to be chronic pancreatitis (2 cases) and ductal adenocarcinoma (1 case).

CONCLUSIONS

Acinar cell carcinoma has a distinctive cytological appearance but is frequently misdiagnosed on cytology. Immunocytochemistry is useful for identifying acinar differentiation.

Metastatic mixed acinar-neuroendocrine carcinoma of the pancreas to the liver: a cytopathology case report with review of the literature

A case of metastatic mixed acinar-neuroendocrine carcinoma (MANEC) of the pancreas to the liver is reported. A diagnostic percutaneous US-guided FNA and core biopsy of a liver nodule was performed. The FNA smears were cellular and showed neoplastic cells in clusters with acinar formation, isolated single cells, and scattered naked nuclei. The cytoplasm was finely granular. The nuclei were relatively uniform, some with speckled chromatin and prominent nucleoli. The immunohistochemistry performed on the cell block showed strong positivity for cytokeratin AE1/AE3, chromogranin, and synaptophysin. Furthermore, the tumor cells were weakly positive for α1-antichymotrypsin. The Ki-67 mitotic index was up to 50%. Based on the morphology and supporting immunohistochemical stains, the final cytopathologic diagnosis rendered was "Positive for malignant cells. Carcinoma with mixed acinar and endocrine features." To our knowledge, this is the first report of a metastatic MANEC to the liver diagnosed based on cytology with confirmatory histology. The difficulties in the cytopathologic diagnosis and differential diagnosis of MANEC are discussed in this article.

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Mixed ductal-endocrine carcinoma of pancreas

Mixed ductal-endocrine carcinomas of the pancreas are extremely rare and show morphologically separate ductal adenocarcinoma and endocrine components. Prognostically, they are more aggressive than pure endocrine neoplasms. These are true 'mixed' neoplasms and are distinct from ductal adenocarcinomas with scattered endocrine cells (in which the endocrine component is non-neoplastic). A mixed ductal endocrine carcinoma in a 73-year-old male is reported.

PAX8 expression reliably distinguishes pancreatic well-differentiated neuroendocrine tumors from ileal and pulmonary well-differentiated neuroendocrine tumors and pancreatic acinar cell carcinoma

PAX (paired box) genes encode a family of transcription factors that regulate organogenesis in a variety of organs. Very little is known about the role of PAX8 in endocrine cell development and the expression of PAX8 in neuroendocrine tumors. The purpose of this study was to analyze PAX8 immunohistochemical expression in gastroenteropancreatic and pulmonary well-differentiated neuroendocrine tumors to determine whether PAX8 can reliably distinguish pancreatic neuroendocrine tumors from neuroendocrine tumors of other anatomic sites and other pancreatic non-ductal neoplasms. In total, 221 well-differentiated neuroendocrine tumors were evaluated: 174 primary neuroendocrine tumors (66 pancreatic, 31 ileal, 21 pulmonary, 20 gastric, 17 rectal, 11 appendiceal, and 8 duodenal) and 47 neuroendocrine tumors metastatic to the liver (31 pancreatic, 11 ileal, 2 pulmonary, 2 duodenal, and 1 rectal). Fifteen solid-pseudopapillary neoplasms and six acinar cell carcinomas of the pancreas were also evaluated. PAX8 was positive in 49/66 (74%) primary pancreatic neuroendocrine tumors. PAX8 expression did not correlate with World Health Organization categorization, grade, size, functional status, or the presence of liver or lymph node metastasis. PAX8 expression was identified in 0/31 (0%) ileal, 0/21 (0%) pulmonary, 2/20 (10%) gastric, 5/17 (29%) rectal, 1/11 (9%) appendiceal, and 6/8 (75%) duodenal neuroendocrine tumors. PAX8 was positive in 4/15 (27%) solid-pseudopapillary neoplasms of the pancreas, whereas all acinar cell carcinomas (0/6) lacked immunoreactivity. Among liver metastases, only pancreatic neuroendocrine tumors (20/31, 65%) were PAX8 positive, whereas no cases of ileal (0/11), pulmonary (0/2), duodenal (0/2), and rectal (0/1) neuroendocrine tumor metastases were PAX8 positive. PAX8 is expressed in primary and metastatic pancreatic well-differentiated neuroendocrine tumors, and its expression can reliably distinguish pancreatic from ileal and pulmonary well-differentiated neuroendocrine tumors. Duodenal neuroendocrine tumors and a subset of rectal, gastric, and appendiceal neuroendocrine tumors may also express PAX8. PAX8 expression can distinguish pancreatic neuroendocrine tumors from acinar cell carcinomas, but its utility in distinguishing neuroendocrine tumors from solid-pseudopapillary neoplasms is limited.

Combined typical carcinoid and acinic cell tumor of the lung

We report a case of combined typical carcinoid and acinic cell tumor of the lung in a 55-year-old female. A chest radiograph revealed an abnormal shadow. Computed tomography (CT) showed a tumor in the S3 segment of the right lung. The transbronchial biopsy yielded a diagnosis of non-small-cell lung cancer. Radical surgery was performed. The pathological diagnosis was combined typical carcinoid and acinic cell tumor of the right lung. This is third case of this tumor which has been reported.

Mayo Clinic experience with very rare exocrine pancreatic neoplasms

OBJECTIVES

Limited data are available to guide the management of very rare exocrine neoplasms of the pancreas (VREP). Available evidence suggests that VREP have different risk factors and prognoses from those of adenocarcinoma of the pancreas. The primary objectives for this study were to determine the survival, comorbidities, and response to treatment of patients seen at Mayo Clinic with VREP.

METHODS

We reviewed patients from 1975 to 2005 who had VREP and compared them to patients with adenocarcinomas that were matched for TNM, grade, and decade of treatment.

RESULTS

Sixty-six patients with VREP were identified. The most commonly identified neoplasms were acinar cell carcinoma (n = 15), small cell carcinoma (n = 12), and squamous cell carcinoma (n = 8). Abdominal discomfort and jaundice were the most common presenting symptoms. The median overall survival for patients with VREP, 10.4 months (range, 3.7-23 months), was better than that for matched controls, 8.2 months (range, 4-15.4 months) (P = 0.01). There was no difference in the survival of patients with stage 4 disease between cases, 8 months (range, 2.3-21.8 months), and controls, 6.7 months (range, 2.3-10.8 months) (P = 0.17).

CONCLUSIONS

We present one of the largest series of VREP to date. The overall survival of all patients with VREP was better than matched controls, but no statistical difference was seen between the groups with stage 4 disease.

Imaging findings in a case of mixed acinar-endocrine carcinoma of the pancreas

Mixed acinar-endocrine carcinoma (MAEC) of the pancreas is extremely uncommon. We report here a rare case of MAEC of the pancreas presenting as watery diarrhea. This is the first report in the English-language literature that describes the imaging findings of MAEC of the pancreas, including computed tomography (CT), magnetic resonance (MR) imaging, and MR cholangiopancreatography features.

Endocrine neoplasms of the pancreas: pathologic and genetic features

CONTEXT

Pancreatic endocrine neoplasms (PENs) are diagnostically challenging tumors whose natural history is largely unknown. Histopathology allows the distinction of 2 categories: poorly differentiated high-grade carcinomas and well-differentiated neoplasms. The latter include more than 90% of PENs whose clinical behavior varies from indolent to malignant and cannot be predicted by their morphology.

OBJECTIVES

To review the literature and report on additional primary material about the clinicopathologic features, classification, staging, grading, and genetic features of PENs.

DATA SOURCES

Literature review of relevant articles indexed in PubMed (US National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

The diagnosis of PEN is generally easy, but unusual features may induce misdiagnosis. Immunohistochemistry solves the issue, provided that the possibility of a PEN has been considered. Morphology allows the distinction of poorly differentiated aggressive carcinomas from well-differentiated neoplasms. The World Health Organization classification criteria allow for the discernment of the latter into neoplasms and carcinomas with either benign or uncertain behavior. The recently proposed staging and grading systems hold great promise for permitting a stratification of carcinomas into clinically significant risk categories. To date, inactivation of the MEN1 gene remains the only ascertained genetic event involved in PEN genesis. It is inactivated in roughly one-third of PENs. The degree of genomic instability correlates with the aggressiveness of the neoplasm. Gene silencing by promoter methylation has been advocated, but a formal demonstration of the involvement of specific genes is still lacking. Expression profiling studies are furnishing valuable lists of mRNAs and noncoding RNAs that may advance further the research to discover novel markers and/or therapeutic targets.

Subcutaneous fat necrosis as the presenting feature of a pancreatic carcinoma: the challenge of differentiating endocrine and acinar pancreatic neoplasms

The association between pancreatic panniculitis and pancreatic disease is well described, but differentiation among the neoplastic causes of the syndrome remains difficult due to substantial overlap in histological and immunohistochemical features. We report a case of subcutaneous fat necrosis as the presenting feature in a 61-year-old man with metastatic carcinoma of pancreatic origin. Previous pathological evaluation of the patient's liver biopsy led to an initial diagnosis of adenocarcinoma of unknown primary site. One month later, the patient presented with pancreatic panniculitis, prompting further investigation. Immunohistochemistry was consistent with neuroendocrine differentiation, but the patient rapidly decompensated and died before the evaluation was complete, leaving the definitive diagnosis in question. In our review of the published reports of tumor types associated with pancreatic panniculitis, we found that immunohistochemical staining and electron microscopy can and should be used in conjunction with clinical correlation to accurately differentiate neuroendocrine tumors from carcinomas with acinar cell features. Accurate diagnosis of these tumors is necessary to determine prognosis and define appropriate therapy.

Acinar cell carcinoma of the pancreas metastatic to the ovary: a report of 4 cases

We report 4 cases of acinar cell carcinoma of the pancreas, 3 presenting as metastases in the ovary, the first report of this circumstance, which may pose a broad differential diagnosis and caused significant diagnostic difficulty in all the cases. The average patient age was 57 (range: 28 to 81) years. In 3 cases, the ovarian tumors were detected before the pancreatic tumor; in 1 case, a large abdominal mass and ovarian tumors were discovered synchronously. The ovarian tumors were large, solid, white-tan on gross examination, and bilateral in 3 cases; the single case involving only 1 ovary had 2 discrete masses of tumor. Microscopic examination showed highly cellular neoplasms with a small amount of fibrous stroma. Two cases had a predominant acinar growth pattern of cells with brightly eosinophilic, granular cytoplasm. In 2 cases, the pattern was predominantly solid-cribriform with areas of comedolike necrosis, and the cells had pale eosinophilic, finely granular cytoplasm. Nuclei in all cases were uniform with prominent nucleoli. The main differential diagnostic consideration was well-differentiated neuroendocrine neoplasm (carcinoid tumor); positive immunostaining with antibodies against chymotrypsin and trypsin and negative immunostaining with antibodies against synaptophysin and chromogranin helped exclude this diagnosis. We observed focal alpha-inhibin immunostaining in 2 cases, which may represent a potential diagnostic pitfall, as a Sertoli cell tumor or unusual granulosa cell tumor may also enter the differential diagnosis. Inclusion of antibodies against the pancreatic enzymes chymotrypsin and trypsin in the immunohistochemical panel is critical in establishing the correct diagnosis and should be considered when evaluating ovarian tumors with architectural (mainly acinar) and cytologic (granular eosinophilic cytoplasm) characteristics that should bring a metastatic acinar cell carcinoma into consideration.

Serpin peptidase inhibitor clade A member 1 as a potential marker for malignancy in insulinomas

PURPOSE

The biological behavior of insulinomas cannot be predicted based on histopathologic criteria in which the diagnosis of malignancy is confirmed by the presence of metastases. In this study, microarray and quantitative real-time reverse transcription-PCR were applied to identify differentially expressed genes between malignant and nonmalignant insulinomas to search for useful biomarkers to recognize the metastatic potential of insulinomas.

EXPERIMENTAL DESIGN

Code Link human bioarrays were used to analyze differences in approximately 20,000 genes between six well-differentiated endocrine tumors of benign behavior compared with one well-differentiated endocrine carcinoma (WDEC) and three metastases of endocrine carcinomas (MEC). Quantitative real-time reverse transcription-PCR was used to validate differential expressions of five genes in a series of 35 sporadic insulinomas. Serpin peptidase inhibitor clade A member 1 (SERPINA1; alpha-1-antitrypsin) expression, identified as up-regulated in malignant insulinomas, was also evaluated by immunohistochemistry.

RESULTS

Analysis of microarray data resulted in 230 differentially expressed genes. Gene Ontology analysis identified serine-type endopeptidase activity and serine-type endopeptidase inhibitor activity as pathways presenting significant differential expression. Protease serine 2 and complement factor B (from serine-type endopeptidase activity pathway) were respectively confirmed as up-regulated in well-differentiated endocrine tumors of benign behavior (WDET) and in WDEC/MEC. Angiotensinogen and SERPINA1 (from serine-type endopeptidase inhibitor activity pathway) were confirmed as up-regulated in WDEC/MEC. SERPINA1 was shown to be expressed in 85.7% of malignant versus 14.3% of nonmalignant insulinomas by immunohistochemistry.

CONCLUSIONS

Our data are consistent to the possibility that SERPINA1 is a marker of malignancy in insulinomas. Given the widespread availability of antibody anti-alpha-1-antitrypsin in pathology services, SERPINA1 expression evaluation might be of clinical utility in recognizing patients more likely to develop an aggressive presentation.

Nonductal neoplasms of the pancreas

Although the majority of pancreatic neoplasms are infiltrating ductal adenocarcinomas or other neoplasms with ductal differentiation, neoplasms with acinar, endocrine, mixed, or uncertain differentiation constitute a diverse and distinctive group. The most common and best-characterized nonductal neoplasms are pancreatic endocrine neoplasm, acinar cell carcinoma, pancreatoblastoma, and solid pseudopapillary neoplasm. This review details the clinical and pathologic features of these nonductal neoplasms, highlighting diagnostic criteria including the use of specific immunohistochemical stains to define the cellular differentiation of the neoplasms.

Valosin-containing protein (p97) and Ki-67 expression is a useful marker in detecting malignant behavior of pancreatic endocrine neoplasms

OBJECTIVE

To determine the prognostic value of valosin-containing protein (VCP) expression and the Ki-67 labeling index (LI) in pancreatic endocrine neoplasms (PENs), the present analysis was employed.

METHODS

The Ki-67 LI and VCP expression at the mRNA and protein level were evaluated in 32 patients (12 male and 20 female) with PENs aged from 22 to 73 years (median 49 years). VCP staining intensity in tumor cells was categorized as weaker (level 1) or equal to stronger (level 2) compared to nontumorous islet cells. Ki-67 LI was divided into two categories: level 1, Ki-67 LI < 5%, and level 2, > or = 5%.

RESULTS

Five cases (15.6%) showed level 1 and 25 (84.4%) level 2 VCP expression by immunohistochemistry. A significant association was observed between VCP expression and the malignant behavior of PENs (p < 0.01). All level 1 VCP tumors were benign PENs. Quantitative reverse transcription polymerase chain reaction analysis showed higher VCP mRNA expression in malignant PENs (n = 5) than benign cases (n = 5) (p < 0.05). For Ki-67 LI, 28 cases (87.5%) showed level 1 and 4 (12.5%) level 2 expression. All patients with level 2 Ki-67 LI had metastasis.

CONCLUSION

VCP expression analysis and Ki-67 LI are useful prognosticators for PENs.

Cytokeratin 19 Is a Powerful Predictor of Survival in Pancreatic Endocrine Tumors

The prediction of the behavior of pancreatic endocrine tumors (PETs) is a difficult exercise. CK19, a marker of pancreatic ductal cells, does not stain normal islet cells. Our aim was to evaluate the prognostic value of traditional parameters, including the Capella classification, as well as CK19. We evaluated the clinicopathologic features of 101 curatively resected PETs. The influence on survival of size, functional status of tumor, growth pattern, nuclear grade, mitoses (>2/10 HPF), vascular and perineural invasion, and necrosis was determined. Immunohistochemistry for Ki-67 and CK19 was performed in 45 and 54 cases, respectively. Cases were categorized as per the Capella classification as: benign, borderline, low-grade, and high-grade malignant. The different variables were tested by standard univariate and multivariate analyses. Mitoses (P = 0.03), solid pattern (P = 0.04), necrosis (P = 0.01), vascular invasion (P = 0.003), perineural invasion (P = 0.02), CK19 staining (P = 0.0008), and Ki-67 (P = 0.02) were significant prognostic indicators by univariate analysis while the Capella classification was not significant. By multivariate analysis, only CK19 was significant (P = 0.0008). None of the CK19-negative cases died of disease, while 10 of 28 CK19-positive cases died of disease and 3 are alive with disease. The Capella classification includes malignant tumors in its benign and borderline categories. CK19 is a powerful predictor of survival and can potentially segregate benign and malignant PETs. We suggest that all PETs with any one of the following features be diagnosed as malignant: presence of necrosis, vascular invasion, perineural invasion, or CK19 positivity. We hypothesize that a subgroup of PETs may share a common histogenesis with pancreatic adenocarcinomas.

Combined typical carcinoid and acinic cell tumor of the lung: a heretofore unreported occurrence

We report a primary combined typical carcinoid and acinic tumor of the lung in a 70-year-old man. Although a similar case was reported previously, to the best of our knowledge this is the first case in which the diagnosis is supported by both immunohistochemical and ultrastructural findings. We review the literature and discuss the implications of this finding.