The monoclonal anti-BCL10 antibody (clone 331.1) is a sensitive and specific marker of pancreatic acinar cell carcinoma and pancreatic metaplasia

Pathological complete response with FOLFIRINOX therapy for recurrence of pancreatic acinar cell carcinoma

Pancreatic acinar cell carcinoma (PACC) is a very rare subtype of pancreatic cancer. Due to small number of patients, no standard chemotherapy protocol has been established. We experienced an extremely rare case of PACC with liver metastasis that showed a pathological complete response after modified FOLFIRINOX (mFFX) therapy. A 42-year-old man who underwent distal pancreatectomy for an 80 mm tumor at the pancreatic tail 3 years ago was referred to our hospital in September 2017 for the treatment of a recurrent liver tumor. Percutaneous biopsy revealed an acinar-neuroendocrine carcinoma, similar to the surgical specimen. He received eight cycles of irinotecan plus cisplatin chemotherapy. However, the tumor increased in size, and treatment was switched to mFFX therapy. The tumor in the liver shrank remarkably after nine cycles of mFFX therapy. Conversion surgery was selected, and the patient underwent hepatic left and caudate lobectomy 8 months after administration of mFFX. The resected specimen showed no viable tumor cells, indicating a pathological complete response. The histological diagnosis was reconsidered, and PACC was finally diagnosed via an additional immunohistological review. The patient has remained well with no recurrence for 6 years after surgery. This study is the first to report a case of pathological complete response with mFFX therapy for the recurrence of PACC.

A narrative review on rare types of pancreatic cancer: should they be treated as pancreatic ductal adenocarcinomas?

Pancreatic cancer is one of the deadliest malignancies in humans and it is expected to play a bigger part in cancer burden in the years to come. Pancreatic ductal adenocarcinoma (PDAC) represents 85% of all primary pancreatic malignancies. Recently, much attention has been given to PDAC, with significant advances in the understanding of the mechanisms underpinning disease initiation and progression, along with noticeable improvements in overall survival in both localized and metastatic settings. However, given their rarity, rare histological subtypes of pancreatic cancer have been underappreciated and are frequently treated as PDAC, even though they might present non-overlapping molecular alterations and clinical behavior. While some of these rare histological subtypes are true variants of PDAC that should be treated likewise, others represent separate clinicopathological entities, warranting a different therapeutic approach. In this review, we highlight clinical, pathological, and molecular aspects of rare histological types of pancreatic cancer, along with the currently available data to guide treatment decisions.

Unraveling the enigma: A comprehensive review of solid pseudopapillary tumor of the pancreas

Solid pseudopapillary tumor of the pancreas (SPTP) is a rare neoplasm predominantly observed in young females. Pathologically, CTNNB1 mutations, β-catenin nuclear accumulation, and subsequent Wnt-signaling pathway activation are the leading molecular features. Accurate preoperative diagnosis often relies on imaging techniques and endoscopic biopsies. Surgical resection remains the mainstay treatment. Risk models, such as the Fudan Prognostic Index, show promise as predictive tools for assessing the prognosis of SPTP. Establishing three types of metachronous liver metastasis can be beneficial in tailoring individualized treatment and follow-up strategies. Despite advancements, challenges persist in understanding its etiology, establishing standardized treatments for unresectable or metastatic diseases, and developing a widely recognized grading system. This comprehensive review aims to elucidate the enigma by consolidating current knowledge on the epidemiology, clinical presentation, pathology, molecular characteristics, diagnostic methods, treatment options, and prognostic factors.

Marked intestinal trans-differentiation by autoimmune gastritis along with ectopic pancreatic and pulmonary trans-differentiation

BACKGROUND

Autoimmune gastritis (AIG) is a prevalent chronic inflammatory disease with oncogenic potential that causes destruction of parietal cells and severe mucosal atrophy. We aimed to explore the distinctive gene expression profiles, activated signaling pathways, and their underlying mechanisms.

METHODS

A comprehensive gene expression analysis was conducted using biopsy specimens from AIG, Helicobacter pylori-associated gastritis (HPG), and non-inflammatory normal stomachs. Gastric cancer cell lines were cultured under acidic (pH 6.5) conditions to evaluate changes in gene expression.

RESULTS

Gastric mucosa with AIG had a unique gene expression profile compared with that with HPG and normal mucosa, such as extensively low expression of ATP4A and high expression of GAST and PAPPA2, which are involved in neuroendocrine tumorigenesis. Additionally, the mucosa with AIG and HPG showed the downregulation of stomach-specific genes and upregulation of small intestine-specific genes; however, intestinal trans-differentiation was much more prominent in AIG samples, likely in a CDX-dependent manner. Furthermore, AIG induced ectopic expression of pancreatic digestion-related genes, PNLIP, CEL, CTRB1, and CTRC; and a master regulator gene of the lung, NKX2-1/TTF1 with alveolar fluid secretion-related genes, SFTPB and SFTPC. Mechanistically, acidic conditions led to the downregulation of master regulator and stemness control genes of small intestine, suggesting that increased environmental pH may cause abnormal intestinal differentiation in the stomach.

CONCLUSIONS

AIG induces diverse trans-differentiation in the gastric mucosa, characterized by the transactivation of genes specific to the small intestine, pancreas, and lung. Increased environmental pH owing to AIG may cause abnormal differentiation of the gastric mucosa.

Pancreatic acinar cell carcinoma with pleomorphic and spindle cells: An autopsy-proven case

Pancreatic acinar cell carcinomas are glandular and have amphophilic/eosinophilic cytoplasm, presenting acinar, solid, and trabecular structures. Unusual histological features of acinar cell carcinoma are known, such as oncocytic, pleomorphic, spindle, and clear cell variants, but their clinical significance has not been well described. A man in his 70s was referred to our hospital because of elevated serum pancreatic enzymes. Contrast-enhanced abdominal computed tomography revealed slight swelling of the pancreatic head and suspension of the main pancreatic duct in the pancreatic body. He died only 14 days after admission. Gross findings at autopsy showed an ill-defined tumor located in the pancreatic head, involving the gastric and duodenal walls. Peritoneal dissemination, liver metastases, and lymph node metastases were also observed. Microscopically, tumor cells had moderate-to-severe nuclear atypia and amphophilic cytoplasm showing pleomorphism, and diffusely proliferated in solid pattern without lumina, were admixed with spindle cells. Immunohistochemically, tumor cells including pleomorphic and spindle cells were positive for B-cell lymphoma/leukemia 10 and trypsin. Consequently, the diagnosis was pancreatic acinar cell carcinoma with pleomorphic and spindle cells. We encountered a rare variant of pancreatic acinar cell carcinoma with pleomorphic and spindle cells. Clinically, our case showed rapid progression.

A case of unresectable ectopic acinar cell carcinoma developed in the portal vein in complete response to FOLFIRINOX therapy

A 56-year-old man presented to our hospital for close examination of a mass in the portal vein. CT showed a homogeneously enhanced mass occupying the portal vein. No other lesions suggestive of a primary tumor were detected. Endoscopic ultrasound-guided fine-needle aspiration revealed that the tumor was pathologically acinar cell carcinoma (ACC) based on the positive staining for both BCL-10 and trypsin. He was diagnosed with an ectopic ACC developed in the portal vein. Because the tumor invaded secondary branches of the right intrahepatic portal vein and the superior mesenteric vein, it was considered surgically un-resectable. Therefore, chemotherapy with gemcitabine plus nab-paclitaxel (GEM + nab-PTX) was started. After 2 courses, CT showed progressive disease, so the regimen was switched to FOLFIRINOX. After starting treatment with FOLFIRINOX, the tumor shrank gradually. After 29 courses, CT scan eventually showed disappearance of the tumor and complete response was achieved. After 34 courses, the chemotherapy was discontinued. Since then, the patient has been recurrence-free for 5 years. Our English literature review yielded 6 cases, including this case, of un-resectable ACC in which complete response was achieved by chemotherapy. Our case suggest that platinum-based regimen might be an effective therapy for un-resectable ACC, including ectopic ACC.

Derivation of pancreatic acinar cell carcinoma cell line HS-1 as a patient-derived tumor organoid

Acinar cell carcinoma (ACC) of the pancreas is a malignant tumor of the exocrine cell lineage with a poor prognosis. Due to its rare incidence and technical difficulties, few authentic human cell lines are currently available, hampering detailed investigations of ACC. Therefore, we applied the organoid culture technique to various types of specimens, such as bile, biopsy, and resected tumor, obtained from a single ACC patient. Despite the initial propagation, none of these organoids achieved long-term proliferation or tolerated cryopreservation, confirming the challenging nature of establishing ACC cell lines. Nevertheless, the biopsy-derived early passage organoid developed subcutaneous tumors in immunodeficient mice. The xenograft tumor histologically resembled the original tumor and gave rise to infinitely propagating organoids with solid features and high levels of trypsin secretion. Moreover, the organoid stained positive for carboxylic ester hydrolase, a specific ACC marker, but negative for the duct cell marker CD133 and the endocrine lineage marker synaptophysin. Hence, we concluded the derivation of a novel ACC cell line of the pure exocrine lineage, designated HS-1. Genomic analysis revealed extensive copy number alterations and mutations in EP400 in the original tumor, which were enriched in primary organoids. HS-1 displayed homozygous deletion of CDKN2A, which might underlie xenograft formation from organoids. Although resistant to standard cytotoxic agents, the cell line was highly sensitive to the proteasome inhibitor bortezomib, as revealed by an in vitro drug screen and in vivo validation. In summary, we document a novel ACC cell line, which could be useful for ACC studies in the future.

Misunderstood Gastric Perforation of a Pancreatic Acinar Cell Carcinoma: A Wolf in Sheep’s Clothing

A 70-year-old man was admitted to the Emergency Department (ED) for marked asthenia and severe anemia. In addition, a high level of lipase was found. During hospitalization, a locally advanced gastric cancer was diagnosed, with endoscopic evidence of a large polyploid formation originating under the cardias that occupied most of the gastric lumen. A total body CT scan was performed before surgery; the tumor affected the posterior gastric wall, with tenacious infiltration of the pancreatic body. Therefore, we performed a total gastrectomy with esophageal jejunum anastomosis and reconstruction of intestinal continuity according to Roux, distal spleno-pancreatectomy, and cholecystectomy. At histology, a pancreatic acinar cell carcinoma (PACC) with full thickness infiltration of the gastric wall was diagnosed. Acinar cell carcinomas are highly aggressive neoplasms, and surgical resection, when feasible, is the treatment of choice regardless of size, also because the role of neoadjuvant or adjuvant chemo- or radiotherapy remains uncodified.

AGAP3: A novel BRAF fusion partner in pediatric pancreatic-type acinar cell carcinoma

Most available molecular data on pancreatic acinar cell carcinoma (PACC) are provided by studies of adult cases. BRAF, RAF1, or RET rearrangements have been described in approximately 30% of cases. To the best of our knowledge, only seven cases with molecular data have been reported in pediatric PACC. We report here the comprehensive study of a pancreatic-type ACC from a 6-year-old patient. We detected an AGAP3::BRAF fusion. This result showing a BRAF rearrangement demonstrates a molecular link between adult and pediatric PACC. Moreover, it identifies AGAP3, a gene located at 7q36.1 that encodes a major component of the N-methyl-d-aspartate (NMDA) receptor signaling complex, as a partner gene of BRAF. The variability of BRAF partners is consistent with a driver role of BRAF alterations in PACC. The identification of such alterations is noteworthy for considering the use of MEK inhibitors in metastatic cases. We did not detect associated genomic instability. The better outcome of pediatric cases might be related to their stable genomic background.

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.

The Diagnostic Challenge of Evaluating Small Biopsies from the Pancreatobiliary System

Examination of fine needle aspirations and small core biopsies of the pancreas can be an extremely difficult and treacherous area for the diagnostic pathologist. The pancreas often yields small and often fragmented specimens, which, in combination with the morphologic overlap between numerous neoplastic and nonneoplastic mimickers, generate multiple potential diagnostic pitfalls. The authors review this challenging topic and provide insight into resolving these pitfalls using morphologic pattern recognition and ancillary testing.

Clinicopathological characteristics of pancreatic acinar cell metaplasia associated with Helicobacter pylori infection

Background

Pancreatic acinar cell metaplasia (PACM) has been rarely reported in the gastric mucosa. In the present study, we aimed to elucidate the clinical and pathological characteristics of PACM associated with Helicobacter pylori (H. pylori).

Method

5930 patients who underwent five- or two-point gastric biopsy according to the updated Sydney system (USS) by upper gastrointestinal endoscopy were enrolled. The patients were categorized into current H. pylori infection (CHI), post-H. pylori eradication (PHE), and non-H. pylori infection (NHI) groups according to the H. pylori infection status, and the frequency and location of PACM were compared. Additionally, a case–control study was performed to compare the USS scores between patients with CHI and PACM and those with CHI but not PACM.

Result

The frequencies of PACM were 0.49% (10/2039), 0.75% (25/3332), and 0% (0/559) in the CHI, PHE, and NHI groups, respectively. PACM was found in the greater curvature of the antrum in 33 of the 35 patients with PACM. Among the patients with CHI, the inflammation scores in the greater curvature of the antrum and the greater curvature of the corpus were lower in patients with PACM than in those without PACM.

Conclusion

Although rarely reported in the gastric mucosa, PACM was closely related to H. pylori infection, especially in the antrum, and was associated with relatively mild inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02338-2.

An update on the development of concepts, diagnostic criteria, and challenging issues for neuroendocrine neoplasms across different digestive organs

Digestive neuroendocrine neoplasms (NENs) are a group of heterogeneous neoplasms found throughout the digestive tract, with different behaviour and genetic background. In the last few years, nomenclature and WHO/UICC classifications of digestive NENs have changed, and molecular classifications have emerged, especially in pancreatic locations. Increasing patho-molecular details are needed to diagnose the different categories of NEN, including the use of helpful immunohistochemical markers. In this review, we address these topics in three successive chapters. We first briefly review recent updates in classifications, discuss important grading and proliferating issues and advances in the molecular understanding of NEN. Then, we provide an update on diagnosis, including the most important differential diagnoses of NEN, with a focus on high-grade neoplasms and mixed tumours. Finally, we highlight a variety of currently used and next-generation predictive and prognostic biomarkers as well as biomarkers of tumour origin and describe some site specificities of gastrointestinal NEN. We specifically focus on biomarkers available to pathologists with the potential to change the way patients with NEN are diagnosed and treated.

Neuroendocrine neoplasms of the pancreas: diagnosis and pitfalls

Common to neuroendocrine neoplasms of the pancreas is their expression of synaptophysin, chromogranin A, and/or INSM1. They differ, however, in their histological differentiation and molecular profile. Three groups can be distinguished: well-differentiated neuroendocrine neoplasms (neuroendocrine tumors), poorly differentiated neuroendocrine neoplasms (neuroendocrine carcinomas), and mixed neuroendocrine-non-neuroendocrine neoplasms. However, the expression of synaptophysin and, to a lesser extent, also chromogranin A is not restricted to the neuroendocrine neoplasms, but may also be in a subset of non-neuroendocrine epithelial and non-epithelial neoplasms. This review provides the essential criteria for the diagnosis of pancreatic neuroendocrine neoplasms including diagnostic clues for the distinction of high-grade neuroendocrine tumors from neuroendocrine carcinomas and an algorithm avoiding diagnostic pitfalls in the delineation of non-neuroendocrine neoplasms with neuroendocrine features from pancreatic neuroendocrine neoplasms.

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.

[Rare pancreatic tumors]

Beyond pancreatic ductal adenocarcinoma, which is by far the most frequent pancreatic neoplasm, a great variety of tumors occur in the pancreas. They include solid and cystic masses and epithelial and nonepithelial neoplasms, and they show a great diversity in their biological behavior, ranging from benign tumors to highly aggressive neoplasms. As examples of rare pancreatic tumors, clinical, morphological, and molecular aspects of acinar cell carcinoma, pancreatoblastoma, solid pseudopapillary neoplasm, and serous cystic neoplasms are presented and discussed.

Clinical Analysis of Acinar Cell Carcinoma of the Pancreas: A Single-Center Experience of 45 Consecutive Cases

Backgrounds:

Acinar cell carcinoma of the pancreas is a rare malignancy, and its features remain unclear. We aimed to analyze the clinical characteristics, treatment and prognosis of acinar cell carcinoma with our institutional case series.

Methods:

Patients diagnosed with acinar cell carcinoma in our hospital between 2005 and 2019 were reviewed. Investigations on clinicopathological features, treatment details and long-term survival were performed.

Results:

A total of 45 pathologically confirmed acinar cell carcinomas were identified. The median age at diagnosis was 58 years with a male-to-female ratio of 3.1:1. There were 24 (53.3%) localized, 5 (11.1%) locally advanced and 16 (35.6%) metastatic cases, with a pancreatic head-to-body/tail ratio of 1:1.4 for all the primary lesions. In the localized group, there were 10 pancreatoduodenectomy, 12 distal pancreatectomy, 1 total pancreatectomy, and 1 distal pancreatectomy combined with proximal gastrectomy. Among the locally advanced and metastatic cases, 13 patients received chemotherapy, 1 received concurrent radiochemotherapy, 1 underwent synchronous resection of primary tumor and liver metastasis, 1 underwent palliative operation, 1 underwent exploratory laparotomy, and 4 required no treatment. The median overall survival of this series was 18.9 months with a 5-year survival rate of 19.6%. Moreover, the resected acinar cell carcinoma patients were associated with prolonged survival compared with the unresected cases (36.6 vs. 8.5 months, P < 0.001).

Conclusions:

Surgical resection could improve the long-term survival of acinar cell carcinoma patients, which might also improve the prognosis of selected metastatic cases. Large-scale studies are needed to further clarify the biological behavior and clinical features, and to seek the optimal treatments.

Pancreatic Solid Pseudopapillary Neoplasm: Key Pathologic and Genetic Features

CONTEXT.—

Solid pseudopapillary neoplasm of the pancreas is a low-grade malignant tumor generally associated with a good prognosis. Solid pseudopapillary neoplasms show peculiar morphologic features, but sometimes the differential diagnosis with other pancreatic neoplasms (ie, pancreatic neuroendocrine tumors) can be a challenging task, especially in cytologic or biopsy specimens. In these cases immunohistochemistry is a useful tool, but the diagnostic utility of several proposed immunohistochemical markers is questionable. In recent years, despite several attempts to characterize the pathogenetic, molecular, and prognostic features of solid pseudopapillary neoplasms, they still remain unclear.

OBJECTIVE.—

To give the reader a comprehensive update on this entity.

DATA SOURCES.—

The PubMed database (US National Library of Medicine) was searched using the following string: pseudopapillary tumor [AND/OR] neoplasm [AND/OR] pancreas. All articles written in English were included. In addition, because a heterogeneous terminology has been used in the past to define solid pseudopapillary neoplasms, the reference lists of each paper selected in the PubMed database were also reviewed.

CONCLUSIONS.—

This review gives a comprehensive update on the pathologic, clinical, and molecular features of solid pseudopapillary neoplasms, particularly addressing issues and challenges related to diagnosis. In addition, we have tried to correlate the molecular alterations with the morphologic and clinical features.

Pancreatic Neoplasms With Acinar Differentiation: A Review of Pathologic and Molecular Features

CONTEXT.—

Pancreatic acinar lesions encompass a broad spectrum of malignant tumors and benign reactive processes affecting both adults and children, with clinical, pathologic, and molecular features that are distinct from more common ductal neoplasms. Accurate morphologic diagnosis and molecular assessment of these uncommon neoplasms is critical for effective patient care.

OBJECTIVE.—

To review the clinical, pathologic, and molecular features of pancreatic neoplasms with acinar differentiation, the most common of which is acinar cell carcinoma but which also includes mixed carcinomas with acinar components, cystic acinar lesions, and pancreatoblastoma.

DATA SOURCES.—

We assessed the current primary literature, as well as recently updated diagnostic manuals.

CONCLUSIONS.—

Pancreatic acinar neoplasms are a morphologically and molecularly heterogeneous group of diseases that are characterized by acinar differentiation of at least a subset of the neoplastic cells, defined either morphologically (granular cytoplasm, single prominent nucleoli) or immunohistochemically. Squamoid nests are a key morphologic feature of pancreatoblastoma. Alterations in WNT signaling and chromosomal 11p loss are common molecular features of both acinar cell carcinoma and pancreatoblastoma. Targetable molecular alterations in acinar carcinoma include BRAF rearrangements and DNA repair defects, including mismatch repair deficiency and BRCA pathway defects. For practicing pathologists, morphologic recognition of such acinar neoplasms is critical, and in the future, molecular diagnostics to identify lesions susceptible to targeted therapy will likely form an important component of patient care.

Pyloric, pseudopyloric, and spasmolytic polypeptide-expressing metaplasias in autoimmune gastritis: a case series of 22 Japanese patients

There are two types of pyloric gland-like metaplasia in the corpus of stomach: pyloric and pseudopyloric metaplasias. They show the same morphology as the original pyloric glands in H&E staining. Pseudopyloric metaplasia is positive for pepsinogen (PG) I immunohistochemically, whereas pyloric metaplasia is negative. Recently, spasmolytic polypeptide-expressing metaplasia (SPEM) is proposed for pyloric gland-like metaplasia mainly in animal experiments. SPEM expresses trefoil factor family 2 (TFF2) and is often considered synonymous with pseudopyloric metaplasia. We reviewed consecutive 22 Japanese patients with autoimmune gastritis (AIG) to investigate TFF2 expression in pyloric and pseudopyloric metaplasias by counting all pyloric gland-like glands in biopsy specimens taken from greater curvature of the middle corpus according to the Updated Sydney System. Pyloric metaplasia was seen in all the 22 cases, and pseudopyloric metaplasia was found in 15 cases. Of 1567 pyloric gland-like glands in all the cases, 1381 (88.1%) glands were pyloric metaplasia glands, and the remaining 186 (11.9%) glands were pseudopyloric metaplasia glands. TFF2 expression was observed in pyloric or pseudopyloric metaplasia glands in 20 cases. TFF2 expression was recognized in 409 of 1381 (26.9%) pyloric metaplasia glands and 27 of 186 (14.5%) pseudopyloric metaplasia glands (P<0.01, chi-square test). In conclusion, SPEM was not always the same as pseudopyloric metaplasia in human AIG, and the majority of metaplasia in AIG was not pseudopyloric but pyloric metaplasia.

Looking into digestive mixed neuroendocrine - nonneuroendocrine neoplasms: subtypes, prognosis, and predictive factors

Mixed neuroendocrine - nonneuroendocrine neoplasms (MiNENs) of the digestive system represent a challenge for both pathologists and clinicians. Their nomenclature has changed several times, and their diagnostic criteria, classification and clinical behaviour have been matter of debate over the years. Although several attempts have been made to elucidate the pathogenesis and biology of MiNENs, some issues remain open. This review will provide: a historical background that helps in understanding the evolution of the concept and nomenclature of mixed neoplasms; a revision of the knowledge on this topic, including molecular aspects, to give the reader a comprehensive and practical overview on this challenging field of pathology; a focus on the diagnostic criteria and on the determination of prognostic and predictive factors; and a description of the different tumour types in the different sites of origin.

Carboxypeptidase A1 and regenerating islet-derived 1α as new markers for pancreatic acinar cell carcinoma

Acinar cell carcinoma (ACC) is a rare tumor that differentiates toward pancreatic acinar cells and shows evidence of pancreatic enzyme production. Mixed acinar-neuroendocrine carcinoma (MANC) is defined as having more than 30% of both acinar and neuroendocrine cell types as per immunohistochemistry analysis. Trypsin is currently the most commonly used stain for acinar differentiation. In this study, we investigate the utility of two novel markers, carboxypeptidase A1 (CPA1) and regenerating islet-derived 1α (REG1a), in diagnosing ACC/MANC. Immunohistochemical staining for CPA1 and REG1a was performed on 14 cases of ACC and 5 cases of MANC as well as on 80 other pancreatic tumors including 20 cases each of ductal adenocarcinoma, well-differentiated neuroendocrine tumor, mucinous cystic neoplasm, and solid pseudopapillary tumor. All ACCs and MANCs were positive for CPA1 (all diffuse) and REG1a (12 diffuse, 4 patchy, and 3 focal). A diffuse or patchy staining pattern was significantly more common in ACC/MANC cases (100% diffuse/patchy for CPA1 and 84% for REG1a) than in other pancreatic tumors (5% diffuse/patchy for CPA1 and 7.5% for REG1a), with a P-value of <0.0001 for both CPA1 and REG1a. The sensitivity and specificity of diffuse/patchy staining for CPA1 and REG1a in diagnosing pancreatic ACC/MANC were 100% and 95% for CPA1 and 84% and 93% for REG1a, respectively. In conclusion, CPA1 and REG1a are sensitive markers for ACC that can be used as additional acinar cell differentiation markers to help in the diagnosis of pancreatic ACC and MANC. A negative result for CPA1 virtually excludes ACC/MANC.

Acinar cell carcinoma of the pancreas: a clinicopathologic and cytomorphologic review

Acinar cell carcinoma (ACC) is a rare malignancy of the pancreas with unique clinical, molecular, and morphologic characteristics. Clinically, these cancers can present with hypersecretory syndrome caused by the release of lipase into the circulation. Surgical resection is the treatment of choice for patients with organ-confined disease; however, with recent advances in precision medicine, therapies targeting the distinct molecular profile of ACC are on the horizon. Cytomorphologic features of ACC have been well described in the literature; and in conjunction with available clinical data and appropriate ancillary studies, an accurate diagnosis can be rendered in most instances. The aim of the current article is to present a comprehensive review of ACC based on available literature while attempting to shed light on some of its key histologic and cytologic characteristics.

Immunohistochemistry in the diagnosis and classification of neuroendocrine neoplasms: what can brown do for you?

This review is based on a presentation given at the Hans Popper Hepatopathology Society companion meeting at the 2019 United States and Canadian Academy of Pathology Annual Meeting. It presents updates on the diagnosis and classification of neuroendocrine neoplasms, with an emphasis on the role of immunohistochemistry. Neuroendocrine neoplasms often present in liver biopsies as metastases of occult origin. Specific topics covered include 1. general features of neuroendocrine neoplasms, 2. general neuroendocrine marker immunohistochemistry, with discussion of the emerging marker INSM1, 3. non-small cell carcinoma with (occult) neuroendocrine differentiation, 4. the WHO Classification of neuroendocrine neoplasms, with discussion of the 2019 classification of gastroenteropancreatic neoplasms, 5. use of Ki-67 immunohistochemistry, 6. immunohistochemistry to assign site of origin in neuroendocrine metastasis of occult origin, 7. immunohistochemistry to distinguish well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma, 8. lesions frequently misdiagnosed as well-differentiated neuroendocrine tumor, and 9. required and recommended data elements for biopsies and resections with associated immunohistochemical stains. Next-generation immunohistochemistry, including lineage-restricted transcription factors (e.g., CDX2, islet 1, OTP, SATB2) and protein correlates of molecular genetic events (e.g., p53, Rb), is indispensable for the accurate diagnosis and classification of these neoplasms.

Pancreatic Ductal Adenocarcinoma and Its Precursor Lesions: Histopathology, Cytopathology, and Molecular Pathology

Pancreatic ductal adenocarcinoma is one of the most aggressive malignant neoplasms with poor outcomes. At the time of diagnosis, the disease is usually at an advanced stage and only a minority is eligible for surgical resection. To improve the prognosis, it is essential to diagnose and treat the disease in an early stage before its progression into an invasive disease. This article reviews clinical features, histopathology, cytopathology, and molecular alterations of pancreatic ductal adenocarcinoma and its precursors. Moreover, we review a recently updated two-tier classification system for precursor lesions, new findings in premalignant cystic neoplasms, and recently updated staging criteria for invasive carcinoma based on the Cancer Staging Manual, eighth edition, from the American Joint Committee on Cancer. Finally, we discuss the potential clinical applications of the rapidly growing molecular and genetic information of pancreatic cancer and its precursors.

A Clinicopathologic and Molecular Update of Pancreatic Neuroendocrine Neoplasms With a Focus on the New World Health Organization Classification

CONTEXT.—

According to the 2017 World Health Organization classification, pancreatic neuroendocrine neoplasms (PanNENs) include a new category of pancreatic neuroendocrine tumor, grade 3, which is often difficult to differentiate from pancreatic neuroendocrine carcinoma. However, pancreatic neuroendocrine tumor grade 3 and pancreatic neuroendocrine carcinoma are distinct entities with very different clinical presentation, prognosis, and therapeutic strategies. Recent discoveries on the molecular characteristics of pancreatic neuroendocrine tumors also play an essential role in the pathologic differential diagnosis of PanNENs. In addition, the histopathologic varieties of PanNENs bring in many differential diagnoses with other pancreatic neoplasms, especially acinar cell carcinoma, solid pseudopapillary neoplasm, and ductal adenocarcinoma.

OBJECTIVE.—

To provide a brief update of the World Health Organization classification; the clinical, histopathologic, immunohistochemical, and molecular characteristics; and the differential diagnoses and biological behavior of PanNENs.

DATA SOURCES.—

Analysis of the pertinent literature (PubMed) and authors' clinical practice experience based on institutional and consultation materials.

CONCLUSIONS.—

The evolving clinical, histopathologic, immunohistochemical, and molecular features of PanNENs are reviewed. Important differential diagnoses with other neoplasms of the pancreas are discussed.

Acinar cell carcinoma of the pancreas with thyroid-like follicular features: first description of a new diagnostic challenging subtype

Acinar cell carcinomas (ACCs) of the pancreas are a heterogeneous group of neoplasms showing a wide spectrum of morphological features including acinar, solid, glandular, and trabecular architecture. In addition, uncommon cytological aspects have recently been described and include oncocytic, spindle, clear, and pleomorphic cell types. This wide histological spectrum represents a challenge in the diagnostic task for pathologists. Molecular mechanisms involved in the onset and progression of ACCs are not completely known, but, in general, they differ from those observed in ductal adenocarcinomas or neuroendocrine neoplasms of the pancreas and frequently include alterations in the APC/β-catenin pathway. In the present paper, we describe a new variant of ACC showing thyroid-like follicular features and CTNNB1 mutation. This phenotype needs to be included in the spectrum of morphological presentation of ACC.

Gastric mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) with pancreatic acinar differentiation: a case report

Background

Gastric mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are infrequently encountered in routine practice. Some gastric neuroendocrine carcinomas (NECs) have a variety of differentiation patterns; however, pancreatic acinar differentiation in gastric NECs is rare. The molecular abnormalities of NECs with pancreatic acinar differentiation are not well understood.

Case presentation

A 67-year-old male with a gastric MiNEN with pancreatic acinar differentiation without any symptoms. The tumor consisted of two components, including both glandular and solid histological features. Although the former component was a common type of adenocarcinoma, the latter showed endocrine differentiation and expressed pancreatic acinar enzymes immunohistochemically. A positive signal with the anti-BCL10 antibody, which detects one of the pancreatic acinar enzymes, was also present specifically in the latter component. We also examined TP53 genomic mutations, DNA methylation status, and allelic imbalance (AI), which is an indicator of tumor aggressiveness. Although both components of this tumor showed no genomic mutation and a low methylation epigenotype, the frequency of AI was higher in the acinar-endocrine component than in the adenocarcinomatous component. The finding of AI indicated the progression of the conventional adenocarcinoma to an acinar-endocrine component and identified the aggressive potential of the acinar-endocrine component.

Conclusions

We report a rare case of gastric MiNEN with pancreatic acinar differentiation. AI analysis revealed tumor progression and aggressiveness. In addition, the usefulness of the anti-BCL10 antibody for detecting the acinar-endocrine component was suggested.

Ancillary Techniques in Cytologic Specimens Obtained from Solid Lesions of the Pancreas: A Review

Advanced methods of molecular characterization have elucidated the genetic, epigenetic, and proteomic alterations associated with the broad spectrum of pancreatic disease, particularly neoplasia. Next-generation sequencing, in particular, has revealed the genomic diversity among pancreatic ductal adenocarcinoma, neuroendocrine and acinar tumors, solid pseudopapillary neoplasm, and other pancreatico-biliary neoplasms. Differentiating these entities from one another by morphologic analysis alone may be challenging, especially when examining the small quantities of diagnostic material inherent to cytologic specimens. In order to enhance the sensitivity and specificity of pancreatic cytomorphology, multiple diagnostic, prognostic, and predictive ancillary tests have been and continue to be developed. Although a great number of such tests have been developed for evaluation of specimens collected from cystic lesions and strictures, ancillary techniques also play a significant role in the evaluation of cytologic specimens obtained from solid lesions of the pancreas. Furthermore, while some tests have been developed to differentiate diagnostic entities from one another, others have been developed to simply identify dysplasia and malignancy. Ancillary studies are particularly important in the subset of cases for which cytomorphologic analysis provides a result that is equivocal or insufficient to guide clinical management. Selection of appropriate ancillary testing modalities requires familiarity with both their methodology and the molecular basis of the pancreatic diseases for which testing is being performed.

A case of multicentric pancreatic mixed acinar-ductal carcinoma diagnosed by a yogurt-like cell clump flowing from the papilla of Vater

BACKGROUND

Histological confirmation is needed when the pancreatic lesions is uncertain for neoplastic or nonneoplastic. Current case with multicentric pancreatic carcinomas showing indefinite clinical images was successfully diagnosed by a biopsy of a novel object expelled from the papilla.

CASE PRESENTATION

A 71-year-old male was referred because of elevated serum pancreatic enzymes. Computed tomography revealed an unclear low-density area in the pancreatic body without evidence of tumor and mild dilation of the upstream main pancreatic duct (MPD). Other images, including abdominal ultrasound, endoscopic ultrasound, and magnetic resonance imaging, did not demonstrate cancerous findings. Endoscopic retrograde cholangiopancreatography showed a crab-claw-like obstruction in the MPD. Surprisingly, the component constituting the obstruction was moved by contrast injection and spilled out of the papilla orifice as a yogurt-like white object. Biopsy of this object by histology revealed a cancer cell clump. Pancreatectomy was performed, and pathology of the resected pancreas showed multiple nodular tumors replacing the acini and extending into the MPD. These neoplasms histologically resembled mixed acinar-ductal carcinoma.

CONCLUSION

Current report presented a rare tumor with multicentric pancreatic lesions, preoperatively diagnosed by a biopsy of an uncommon substance.

Pancreatic Cytopathology

Pancreatic cytopathology, particularly through the use of endoscopic ultrasound-guided fine-needle aspiration (FNA), has excellent specificity and sensitivity for the diagnosis of pancreatic lesions. Such diagnoses can help guide preoperative management of patients, provide prognostic information, and confirm diagnoses in patients who are not surgical candidates. Furthermore, FNA can be used to obtain cyst fluid for ancillary tests that can improve the diagnosis of cystic lesions. In this article, we describe the cytomorphological features and differential diagnoses of the most commonly encountered pancreatic lesions on FNA.

Nonductal Pancreatic Cancers

Nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms, acinar cell carcinomas, and pancreatoblastomas, are uncommon. These entities share overlapping gross, microscopic, and immunohistochemical features, such as well-demarcated solid neoplasms, monotonous cellular tumor cells with little intervening stroma, and abnormal beta-catenin expression. Each tumor also has unique clinicopathologic characteristics with diverse clinical behavior. To differentiate nonductal pancreatic neoplasms, identification of histologic findings, such as pseudopapillae, acinar cell features, and squamoid corpuscles, is important. Immunostainings for acinar cell or neuroendocrine markers are helpful for differential diagnosis. This article describes the clinicopathologic and immunohistochemical features of nonductal pancreatic cancers.

Intraductal Tubulopapillary Neoplasm of the Pancreas: An Update From a Pathologist's Perspective

Context.—Intraductal tubulopapillary neoplasm (ITPN) is a rare intraductal epithelial neoplasm of the pancreas recently recognized as a distinct entity by the World Health Organization classification in 2010. It is defined as an intraductal, grossly visible, tubule-forming epithelial neoplasm with high-grade dysplasia and ductal differentiation without overt production of mucin. The diagnosis can be challenging owing to morphologic overlap with other intraductal lesions and its rarity. While recent advances in molecular genetic studies of ITPN have provided new tools to facilitate clinical diagnosis, the limited number of cases has yielded limited follow-up data to guide management.

Objective.—To provide a clinical, pathologic, and molecular update on ITPN with respect to clinical presentation, imaging findings, histopathologic features, differential diagnosis, biological behavior, molecular characteristics, and treatment options.

Data Sources.—Analysis of the pertinent literature (PubMed) and authors' research and clinical practice experience based on institutional and consultation materials.

Conclusions.—Clinical presentation, imaging findings, histopathology, immunohistochemistry studies, molecular characteristics, prognosis, and treatment options of ITPN are reviewed. Important differential diagnoses with other intraductal neoplasms of the pancreas—especially intraductal papillary mucinous neoplasm—using histopathologic, molecular, and immunohistochemical studies, are discussed. Despite the recent progress, more studies are necessary to assess the biology and genetics of ITPN for a better understanding of the prognostic factors and treatment options.

Gastroenteropancreatic Well-Differentiated Grade 3 Neuroendocrine Tumors: Review and Position Statement

: In 2010, the World Health Organization (WHO) classification of neuroendocrine neoplasms was reviewed and validated the crucial role of the proliferative rate. According to the WHO classification 2010, gastroenteropancreatic neuroendocrine neoplasms are classified as well-differentiated neuroendocrine tumors (NETs) of grade 1 or 2 in up to 84%, or poorly differentiated neuroendocrine carcinomas in 6%-8%. Neuroendocrine carcinomas are of grade G. Recently, a proportion of neuroendocrine tumors presenting a number of mitoses or a Ki-67 index higher than 20% and a well-differentiated morphology have been identified, calling for a new category, well-differentiated grade 3 NET (NET G-3). Studies that have reported the characteristics of neuroendocrine neoplasms have identified more well-differentiated NET G-3 than neuroendocrine carcinomas. The main localizations of NET G-3 are the pancreas, stomach, and colon. Treatment for NET G-3 is not standardized and is balanced between G-1/2 neuroendocrine tumor and neuroendocrine carcinoma treatments. In nonmetastatic neuroendocrine tumors, the European and American guidelines recommended a surgical resection for localized neuroendocrine neoplasm, irrespective of the tumor grading. In NET G-3, chemotherapy is the benchmark if the main treatment goal is reduction of the tumor mass, particularly if it would allow a secondary surgery. In the present work, we review the epidemiology and make recommendations for the management of NET G-3.

IMPLICATIONS FOR PRACTICE

Neuroendocrine tumors presenting a number of mitoses or a Ki-67 index higher than 20% and a well-differentiated morphology have been identified and named well-differentiated grade 3 neuroendocrine tumors (NET G-3). The main localizations of NET G-3 are the pancreas, stomach, and colon. The prognosis is worse than that for NET G-2. In nonmetastatic NET G-3, surgery appeared to be the first option. The chemotherapy regimen in pancreatic NET G-3 should be in line with that implemented in NET G-1/2 when the Ki-67 index is below 55% and should be in line with that implemented for neuroendocrine carcinoma when Ki-67 is above 55%.

Surgical and molecular pathology of pancreatic neoplasms

BACKGROUND

Histologic characteristics have proven to be very useful for classifying different types of tumors of the pancreas. As a result, the major tumor types in the pancreas have long been classified based on their microscopic appearance.

MAIN BODY

Recent advances in whole exome sequencing, gene expression profiling, and knowledge of tumorigenic pathways have deepened our understanding of the underlying biology of pancreatic neoplasia. These advances have not only confirmed the traditional histologic classification system, but also opened new doors to early diagnosis and targeted treatment.

CONCLUSION

This review discusses the histopathology, genetic and epigenetic alterations and potential treatment targets of the five major malignant pancreatic tumors - pancreatic ductal adenocarcinoma, pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, acinar cell carcinoma and pancreatoblastoma.

Novel patient-derived xenograft mouse model for pancreatic acinar cell carcinoma demonstrates single agent activity of oxaliplatin

BACKGROUND

Pancreatic acinar cell carcinoma (PACC) is a rare malignancy, accounting for <1 % of all pancreatic neoplasms. Very few retrospective studies are available to help guide management. We previously reported the case of a patient with metastatic PACC who achieved prolonged survival following doxorubicin treatment. Personalized treatment was based on molecular and in vitro data collected from primary cells developed from their liver metastasis. We now report the characterization of a patient derived tumor xenograft (PDTX) mouse model that originated from this patient's PACC liver metastasis.

METHODS

Fragments of biopsy tissue (5 mm(3)) from PACC liver metastasis were implanted into athymic nude mice. Tumors were grown and passaged from the host mice into new mice to be tested for therapeutic response. Immuno-histochemical (IHC) biomarkers were used to confirm that the PDTX model represents human PACC. The antitumor activities of multiple drugs (5-FU, irinotecan, oxaliplatin, gemcitabine, bevacizumab, erlotinib, doxorubicin and imatinib) were tested. Tumor size was measured over 74 days or until they reached an endpoint volume of ~800 mm(3). Tests to measure serum lipase levels and histological analyses of tumor tissues were also conducted to assess PACC progression and re-differentiation.

RESULTS

The model presented here expresses the same IHC markers found in human PACC. In the chemotherapy study, oxaliplatin produced a prolonged durable growth response associated with increased apoptosis, decreased serum lipase levels and increased healthy acinar cells. Bevacizumab also produced a significant growth response, but the effect was not prolonged as demonstrated by oxaliplatin treatment. The other chemotherapies had moderate to little effect, particularly after treatment ceased. Mutations in DNA repair genes are common in PACC and increase tumor susceptibility to oxaliplatin. To explore this we performed IHC and found no nuclear expression of BRCA2 in our model, indicating a mutation affecting nuclear localization. Gene sequencing confirms BRCA2 has a homozygous gene deletion on Exon 10, which frequently causes a protein truncation.

CONCLUSIONS

In summary, we report the development and characterization of the first and only preclinical PACC PDTX model. Here we show sustained anti-tumor activity of single agent oxaliplatin, a compound that is more effective in tumors that harbor mutations in DNA repair genes. Our data shows that BRCA2 is mutated in our PACC model, which could contribute to the oxaliplatin sensitivity observed. Further studies on this rare PACC model can serve to elucidate other novel therapies, biomarkers, and molecular mechanisms of signaling and drug resistance.

Acinar Cell Carcinoma of the Pancreas: Overview of Clinicopathologic Features and Insights into the Molecular Pathology

Acinar cell carcinomas (ACCs) of the pancreas are rare pancreatic neoplasms accounting for about 1–2% of pancreatic tumors in adults and about 15% in pediatric subjects. They show different clinical symptoms at presentation, different morphological features, different outcomes, and different molecular alterations. This heterogeneous clinicopathological spectrum may give rise to difficulties in the clinical and pathological diagnosis with consequential therapeutic and prognostic implications. The molecular mechanisms involved in the onset and progression of ACCs are still not completely understood, although in recent years, several attempts have been made to clarify the molecular mechanisms involved in ACC biology. In this paper, we will review the main clinicopathological and molecular features of pancreatic ACCs of both adult and pediatric subjects to give the reader a comprehensive overview of this rare tumor type.

ACTH-secreting pancreatic neoplasms associated with Cushing syndrome: clinicopathologic study of 11 cases and review of the literature

Adrenocorticotropic hormone (ACTH)-secreting pancreatic neuroendocrine tumors (PanNETs), although rare, are responsible for about 15% of ectopic Cushing syndrome (CS). They represent a challenging entity because their preoperatory diagnosis is frequently difficult, and clear-cut morphologic criteria useful to differentiate them from other types of PanNETs have not been defined. Ectopic ACTH secretion associated with CS can also be rarely due to pancreatic acinar cell carcinoma (ACC) and pancreatoblastoma, rare tumor types with morphologic features sometimes overlapping those of PanNETs and, for this reason, representing a diagnostic challenge for pathologists. We herein describe the clinicopathologic and immunohistochemical features of 10 PanNETs and 1 ACC secreting ACTH and associated with CS together with an extensive review of the literature to give the reader a comprehensive overview on ACTH-producing pancreatic neoplasms. ACTH-secreting PanNETs are aggressive neoplasms with an immunohistochemical profile that partially overlaps that of pituitary corticotroph adenomas. They are generally large and well-differentiated neoplasms without distinctive histologic features but with signs of aggressiveness including vascular and perineural invasion. They are more frequent in female individuals with a mean age of 42 years. At 5 and 10 years after diagnosis, 35% and 16.2% of patients, respectively, were alive. ACTH-secreting ACCs and pancreatoblastomas are very aggressive pediatric tumors with a poor prognosis. Using an appropriate immunohistochemical panel including ACTH, β-endorphin, trypsin, and BCL10 it is possible to recognize ACTH-secreting PanNETs and to distinguish them from the very aggressive ACTH-secreting ACCs.

E-cadherin-negative acinar cell carcinoma of the pancreas: report of a case showing a solid pseudopapillary growth pattern

E-cadherin expression patterns in acinar cell carcinomas (ACCs) of the pancreas have not been well documented. Herein, we present a hitherto undescribed case of E-cadherin-negative ACC with a solid pseudopapillary growth pattern in a 65-year-old man. We used an antibody against the extracellular domain of E-cadherin. As a further unusual status in ACC, faint β-catenin expression was observed in the cytoplasm of carcinoma cells. Morphological distinction from a solid pseudopapillary neoplasm (SPN) of the pancreas might be problematic in such a case, because of their similarities concerned with the growth pattern and E-cadherin negativity. Without nuclear accumulation of β-catenin, a diagnosis of SPN was almost excluded. Immunoreactivity for trypsin and BCL10 made an accurate diagnosis of ACC to this case. The tumor recurred 10 months post-surgery as rapidly enlarging masses in the liver, presumably indicating the aggressiveness of the E-cadherin-negative phenotype among ACCs.

BCL10 as a useful marker for pancreatic acinar cell carcinoma, especially using endoscopic ultrasound cytology specimens

Acinar cell carcinomas (ACCs) of the pancreas are characterized by the histological and immunohistochemical features of acinar cell differentiation. Recently, BCL10, originally identified as a recurrent t(1;14)(p22;q32) translocation in MALT B-cell lymphoma, was found to be immunohistochemically positive in some solid tumors, including ACC. To evaluate its diagnostic efficacy, we performed BCL10 immunohistochemistry and evaluated molecular markers correlated to pancreatic tumor lineages (neuroendocrine markers and a mutation analysis of KRAS and GNAS) using samples from 126 pancreatic tumors (17 ACCs, 24 pancreatic ductal adenocarcinomas, 4 adenosquamous carcinomas, 9 intraductal papillary mucinous neoplasms, 10 mucinous cystic neoplasms, 44 neuroendocrine tumors, 9 serous cystic tumors and 10 solid-pseudopapillary neoplasms). BCL10 was exclusively expressed in normal acini. In pancreatic tumors, 14 of 17 (82%) ACCs and 2 of 4 (50%) adenosquamous carcinomas were positive, while the other subtypes were almost negative. We subsequently examined the diagnostic utility of BCL10 in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) specimens using 57 pancreatic tumors. BLC10 correctly identified ACCs (9/13) and adenosquamous carcinomas (2/4) but none of the other subtypes (n = 41). Therefore, we suggested that BCL10 expression is a useful marker for acinar cell differentiation, particularly in the diagnosis of EUS-FNA specimens.

Clinicopathologic study of 62 acinar cell carcinomas of the pancreas: insights into the morphology and immunophenotype and search for prognostic markers

Acinar cell carcinoma (ACC) of the pancreas is a very rare tumor that has various morphologic features, which may give rise to diagnostic difficulties. Because of its rarity, many clinicopathologic characteristics remain to be further elucidated, and prognostic factors are yet to be well established. With the aim of better characterizing this carcinoma and searching for prognostic indicators, we collected 62 ACCs and investigated the following parameters: site, size, local infiltration, node and distant metastases, architectural pattern, nuclear atypia, presence of necrosis, lymphovascular and perineural invasion, proliferation, BCL10, trypsin, carboxyl ester lipase, amylase, lipase, PDX1, cytokeratin 19 (CK19), CK7, p53, and β-catenin expression. Twelve cases showing >30% of endocrine cells were reclassified as mixed acinar-neuroendocrine carcinomas, whereas 1 tumor was reclassified as a mixed ductal-acinar carcinoma and was excluded from the statistical prognostic evaluations. BCL10 and trypsin were the most reliable immunohistochemical markers, whereas amylase and lipase were not. Surgery was statistically correlated with a better prognosis (P=0.0008). Among resected tumors there was no difference in survival between ACCs and mixed acinar-neuroendocrine carcinomas, and factors that significantly correlated with poor prognosis were size >6.5 cm (P=0.004), lymph node (P=0.0039) and distant (P=0.008) metastases, and UICC stage (P=0.009). Stage was the only independent prognostic factor at multivariable analysis, and the best prognostic discrimination was observed on grouping together stages I and II and grouping together stages III and IV, suggesting a simplification of the UICC staging for such cancers. In addition, vascular and perineural invasion and CK19 and p53 expression showed a trend for poor prognosis, not reaching statistical significance.

TTF1 expression in normal lung neuroendocrine cells and related tumors: immunohistochemical study comparing two different monoclonal antibodies

Thyroid transcription factor-1 (TTF1) regulates lung morphogenesis and differentiation, and its immunohistochemical expression is used for identifying lung neoplasms. The 8G7G3/1 antibody has been used in previous studies, but a different and more sensitive anti-TTF1 antibody, named SPT24, has become commercially available. Since the immunohistochemical expression of TTF1 in normal lung neuroendocrine (NE) cells has not been previously investigated and its utility in the diagnosis of lung NE tumors is a controversial issue, we studied the TTF1 expression in normal adult and fetal lungs, in 83 pulmonary NE neoplasms, in 131 non-lung NE tumors and in 36 metastases from these neoplasms using these two antibodies. A TTF1 immunoreactivity was demonstrated in normal fetal and adult NE cells when using the SPT24 clone. Conversely, using the 8G7G3/1 antibody, only rare fetal neuroendocrine cells were TTF1 positive while adult NE cells were negative. The SPT24 clone identified TTF1 expression in more carcinoids, most of them peripherally located, and poorly differentiated NE carcinomas than the 8G7G3/1 clone. Non-pulmonary well-differentiated NE tumors were negative for both antibodies. Among the 45 non-pulmonary poorly differentiated NE carcinomas 11% were positive for 8G7G3/1 and 18% for SPT24. TTF1 expression in metastases perfectly reflected that detected in the related primary tumors. Our results indicate that the SPT24 antibody is more sensitive than the 8G7G3/1 clone for labeling lung carcinoids and it appears particularly useful in detecting peripheral neoplasms. In addition, the expression of TTF1 in normal NE cells suggests a possible role for the transcription factor in their development and differentiation.

Localization of carboxyl ester lipase in human pituitary gland and pituitary adenomas

Carboxyl ester lipase (CEL) is an enzyme that hydrolyzes a wide variety of lipid substrates, including ceramides, which are known to show inhibitory regulation of pituitary hormone secretion in experimental models. Because no studies on CEL expression in human pituitary and pituitary adenomas have been reported in the literature, we investigated CEL expression in 10 normal pituitary glands and 86 well-characterized pituitary adenomas [12 FSH/LH cell, 17 α-subunit/null cell, 6 TSH cell, 21 ACTH cell, 11 prolactin (PRL) cell, and 19 GH cell adenomas] using IHC, immunoelectron microscopy, Western blotting, and quantitative RT-PCR. In normal adenohypophysis, CEL was localized in GH, ACTH, and TSH cells. In adenomas, it was mainly found in functioning GH, ACTH, and TSH tumors, whereas its expression was poor in the corresponding silent adenomas and was lacking in FSH/LH cell, null cell, and PRL cell adenomas. Ultrastructurally, CEL was localized in secretory granules close to their membranes. This is the first study demonstrating CEL expression in normal human pituitary glands and in functioning GH, ACTH, and TSH adenomas. Considering that CEL hydrolyzes ceramides, inactivating their inhibitory function on pituitary hormone secretion, our findings suggest a possible role of CEL in the regulation of hormone secretion in both normal and adenomatous pituitary cells.