A series of 64 cases of pancreatic cystic neoplasia from an institutional study of China

Acinar Cystic Transformation of the Pancreas: Report of Three Cases

Acinar cystic transformation (ACT) of the pancreas is a rare non-neoplastic cystic lesion. It is most frequently observed in the head of the pancreas. Despite advances in radiologic imaging methods, preoperative diagnosis of acinar cystic transformation is difficult, it is often confused with other cystic lesions. Here, we report three cases of acinar cystic transformation, one of which showed diffuse involvement of the pancreas, and the remaining two were multilocular localized cystic lesions. We analyzed their histomorphologic and immunohistochemical features. The patients' ages ranged between 15 and 43 years and the ratio of females to males was 2:1. On microscopic examination, the cysts were lined by a single layer of flattened-cuboidal or columnar epithelial cells. The epithelial cells were diffusely positive with trypsin and keratin 7, but patchy with keratin 19. Due to its rarity and lack of radiologic and clinical awareness compared with other pancreatic cystic lesions, preoperative diagnosis of acinar cystic transformation is difficult and not definitive. All cases reported to date have been clinically benign and there is no evidence of recurrence or malignant transformation. The optimal treatment and whether to perform surgery remain controversial.

Mucin 5AC expression is common but unrelated to tumor progression in pancreatic adenocarcinoma

Introduction: Mucin 5AC (MUC5AC) belongs to the family of secreted gel-forming mucins. It is physiologically expressed in some normal mucin producing epithelial cells but also in pancreatic, ovarian, and colon cancer cells. The role of MUC5AC expression in cancer is not fully understood. This study was designed to explore the role of MUC5AC for pancreatic cancer progression, its association to microsatellite instability, and its diagnostic utility. Methods: Mucin 5AC expression was studied immunohistochemically in a tissue microarray (TMA) from 532 pancreatic cancers, 61 cancers of the ampulla Vateri, six acinar cell carcinomas and 12 large sections of pancreatitis. Results: Mucin 5AC staining was interpretable in 476 of 599 (79%) arrayed cancers. Staining was completely absent in normal pancreas and pancreatitis, but frequent in pancreatic cancer. Membranous and cytoplasmic MUC5AC expression was most common in pancreatic adenocarcinomas (71% of 423), followed by carcinomas of the ampulla Vateri (43% of 47), and absent in six acinar cell carcinomas. Mucin 5AC expression was unrelated to tumor phenotype (tumor stage, tumor grade, lymph node, and distant metastasis), and microsatellite instability in ductal adenocarcinomas and carcinomas of the ampulla Vateri. Conclusion: Our study indicates that MUC5AC is an excellent biomarker for pancreatic cancer diagnosis, especially to support the sometimes-difficult diagnosis on small biopsies. Mucin 5AC expression is unrelated to pancreatic cancer aggressiveness.

Calponin and MUC6 complement inhibin as diagnostic immunomarkers of serous cystadenoma in endoscopic ultrasound-guided aspiration/biopsy specimens

AIMS

Because serous cystadenoma (SCA) does not usually require excision, it is critical to distinguish it from differential diagnoses which do, especially neuroendocrine tumour (NET). The gold standard for diagnosing SCA is assessment of endoscopic ultrasound-guided fine needle aspiration/biopsy (EUS-FNAB) material. Inhibin immunohistochemistry aids this assessment, but such positivity is not absolutely sensitive or specific to SCA. The following is the largest known study of SCA EUS-FNAB specimens and the first to compare four potential SCA immunomarkers between themselves and inhibin, compared against NET.

METHODS AND RESULTS

Immunohistochemistry for calponin, mucin 6 (MUC6), glucose transporter 1 (GLUT1) and vascular endothelial growth factor A (VEGFA) was performed on 30 EUS-FNAB and three resection specimens of SCA and 32 EUS-FNAB specimens of NET. GLUT1 and VEGFA were suboptimal as diagnostic immunomarkers of SCA, being expressed by 10 and 44% of NETs, respectively. Further, their expression by cellular constituents of blood which often contaminate EUS-FNAB specimens hampered identification of neoplastic cells, especially in hypocellular samples. While 19% of NETs showed nuclear MUC6 positivity, cytoplasmic expression of the protein showed 100% specificity and sensitivity as an SCA marker. However, assessing MUC6 in EUS-FNAB specimens must also consider the protein's focal expression in physiological pancreatic, gastric or duodenal tissues, which can contaminate these specimens. Calponin was less sensitive (71% versus 100%) but more specific (100% versus 91%) than inhibin, although easier to assess in EUS-FNAB specimens than MUC6.

CONCLUSIONS

Of the four potential immunomarkers of SCA suggested by the existing literature, calponin and MUC6 are useful complementary studies to inhibin for application to EUS-FNAB specimens.

Management of Incidental Pancreatic Cystic Lesions

BACKGROUND

Pancreatic cystic lesions (PCL) are common. They are increasingly detected as an incidental finding of transabdominal ultrasound or cross-sectional imaging. In contrast to other parenchymal organs, dysontogenetic pancreatic cysts are extremely rare. In symptomatic patients the most frequent PCL are acute and chronic pseudocysts. The majority of incidental cystic lesions, however, are neoplasias which have different risks of malignancy.

METHODS

PubMed was searched for studies, reviews, meta-analyses, and guidelines using the following key words: ('pancreatic cystic lesions' OR 'cystic pancreatic lesions' OR 'intraductal papillary mucinous neoplasia' OR 'mucinous cystic neoplasia' OR 'pancreatic cyst' OR 'pancreatic pseudocyst') AND (management OR treatment OR outcome OR prognosis OR diagnosis OR imaging OR 'endoscopic ultrasound' EUS-FNA OR EUS OR 'endoscopic ultrasonography' OR CT OR MRI). Retrieved papers were reviewed with regard to the diagnostic and therapeutic management of incidental PCL.

RESULTS

In addition to clinical criteria, transabdominal ultrasonography including contrast-enhanced ultrasonography, cross-sectional radiological imaging, and endoscopic ultrasound (EUS) are used for diagnostic characterization and risk assessment. EUS plays an outstanding role in differential diagnosis and prognostic characterization of incidental PCL. In a single examination it is possible to perform high-resolution morphological description, perfusion imaging, as well as fine-needle aspiration of cyst content, cyst wall, and solid components. An international consensus guideline has defined worrisome and high-risk criteria for the risk assessment of mucinous pancreatic cysts, which are mainly based on the results of EUS and cross-sectional imaging. Nevertheless, despite diagnostic progress and guideline recommendations, differential diagnosis and management decisions remain difficult. This review will discuss problems in and approaches to the diagnosis of incidental PCL.

CONCLUSION

An evidence-based algorithm for the diagnosis of incidental PCL is proposed.

Surgical resection and outcome of pancreatic cystic neoplasms in China: analysis of a 16-year experience from a single high-volume academic institution

Background

To investigate the clinicopathological features of surgically resected pancreatic cystic neoplasms (PCNs) at a single institution in China.

Methods

The medical charts of patients who operated in the Second Affiliated Hospital, Zhejiang University School of Medicine between 1 January 1997 and 30 June 2013, were pathologically shown to have PCNs.

Results

There was a reliable increase trend not just in the overall number of patients (3 to 75) but additionally in the number of incidentally diagnosed patients across the periods (33.3% to 48.0%). In 83 of 111 cases, preoperative diagnoses matched with pathology, whereas the remaining cases (16/28) were misdiagnosed as pancreatic cancer. The proportion of malignancy in mucin producing neoplasms was 24.3% (9 out of 37). Elevated serum carbohydrate antigen (CA19-9) or carcinoembryonic antigen (CEA) was independently associated with malignancy. The overall survival rate was 96.4%.

Conclusions

The proportion of PCNs within this series differs with that revealed in Western countries. Appropriate preoperative differential diagnosing of PCNs remains challenging. It is strongly recommended that patients with elevated CA19-9 or CEA levels undergo surgical resection.

Genetic markers of malignant transformation in intraductal papillary mucinous neoplasm of the pancreas: a meta-analysis

OBJECTIVES

The objective of this study was to determine the relationship between specific genetic alterations and malignant transformation in intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Quantitative meta-analysis was conducted of studies through October 2010 that adhered to the 1996 World Health Organization guidelines for distinguishing adenoma and borderline IPMN versus carcinoma in surgically resected specimens using a random-effects model. We developed a 6-point scoring system to assess study quality.

RESULTS

Thirty-nine studies (1235 IPMN samples) satisfied the inclusion criteria, and we conducted pooled analysis of 8 genetic markers: MUC1, MUC2, MUC5AC, kRas, p53, hTERT (human telomerase reverse transcriptase), cyclooxygenase 2, and Shh (Sonic hedgehog). Markers having the strongest association with malignant IPMN were hTERT (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-36.7) and Shh (OR, 6.9; 95% CI, 2.4-20.2), whereas MUC5AC (OR, 1.0; 95% CI, 0.1-13.9) and kRas (OR, 2.0; 95% CI, 1.0-4.3) showed weak association with IPMN histologic progression.

CONCLUSIONS

Expression of hTERT is strongly associated with malignant transformation in IPMN, consistent with up-regulation of hTERT as a key step in progression of IPMN to cancer. Expression of kRas and MUC5AC is common but not strongly associated with IPMN histologic progression. The quality criteria used here may guide future reporting of genetic markers related to malignant transformation of IPMN.

Differentiating pancreatic ductal adenocarcinoma from pancreatic serous cystadenoma, mucinous cystadenoma, and a pseudocyst with detailed analysis of cystic features on CT scans: a preliminary study

Objective

To determine whether or not detailed cystic feature analysis on CT scans can assist in the differential diagnosis of pancreatic ductal adenocarcinoma (PDAC) from serous cystadenoma (SCN), mucinous cystadenoma (MCN), and a pseudocyst.

Materials and Methods

This study received Institutional Review Board approval and informed patient consent was waived. Electronic radiology and pathology databases were searched to identify patients with PDAC (n = 19), SCN (n = 26), MCN (n = 20) and a pseudocyst (n = 23) who underwent pancreatic CT imaging. The number, size, location, and contents of cysts, and the contour of the lesions were reviewed, in addition to the wall thickness, enhancement patterns, and other signs of pancreatic and peripancreatic involvement. Diagnosis was based on lesion resection (n = 82) or on a combination of cytological findings, biochemical markers, and tumor markers (n = 6). Fisher's exact test was used to analyze the results.

Results

A combination of the CT findings including irregular contour, multiple cysts, mural nodes, and localized thickening, had a relatively high sensitivity (74%) and specificity (75%) for differentiating PDAC from SCN, MCN, and pseudocysts (p < 0.05). Other CT findings such as location, greatest dimension, or the presence of calcification were not significantly different.

Conclusion

The CT findings for PDAC are non-specific, but perhaps helpful for differentiation. PDAC should be included in the general differential diagnosis of pancreatic cystic neoplasms.

Proteases present in some pancreatic cyst fluids may affect mucin immunoassay by degrading antibodies and antigens

OBJECTIVES

Biomarker detection in pancreatic cyst fluids is of importance to improve the diagnosis of mucinous cystadenoma, a precancerous lesion. However, assay protocols are generally established for serum testing.

METHODS

Immunoradiometric assay of gastric M1/MUC5AC mucin was performed on pancreatic cyst fluids with well-characterized monoclonal antibodies.

RESULTS

Among 1466 pancreatic cyst fluids tested, about 10% to 15% of samples presented abnormal behaviors: (i) radioactivity measured after immunoradiometric assay much lower than the blank of the assay and (ii) increasing dilution of the fluids leading to apparent increase of M1/MUC5AC concentration. In contrast, none of the 109 hepatic cyst fluids tested presented interference.We demonstrate that some (n = 54) interfering fluids cause mucin degradation as well as antibody degradation. Western blot analysis showed that the C-terminal part of the M1/MUC5AC apomucin is most sensitive to degradation.

CONCLUSIONS

The presence of proteases that degrade antibodies as well as mucin may explain the pitfalls observed in 3.6% of the samples. To detect this interference, each fluid has to be systematically tested at 1:100 dilution in the presence of a saturating concentration of M1/MUC5AC mucin standard and in the absence of antiprotease reagents. Detection of interference could prevent false results caused by mucin degradation in situ.

Calponin is expressed in serous cystadenomas of the pancreas but not in adenocarcinomas or endocrine tumors

The diagnosis of serous microcystic adenoma (SMA) is usually straightforward. For small biopsies and/or unusual variants, the differential diagnosis includes other pancreatic or metastatic neoplasms showing cystic or clear cell features. We evaluated immunostains for potential use in the diagnosis of SMA. Cases of SMA were identified from archival files. Tissue cores (2 per block) were arrayed to create a microarray of cores measuring 2mm each. Additionally, microarrays previously constructed from 56 pancreatic adenocarcinomas (PACs) and 64 pancreatic endocrine tumors (PENs) were studied. The microarrays were stained with calponin, chromogranin, CD10, alpha-inhibin, and monoclonal neuron-specific enolase (m-NSE). Subsequently, some were stained with MUC6, melan-A, D2-40, h-caldesmon, smooth muscle actin, and smooth muscle myosin. For SMAs, staining was seen with calponin (85.2%), alpha-inhibin (96.2%), and m-NSE (96.2%). Focal weak staining was seen with MUC6 (65%). All SMAs were negative with chromogranin, CD10, melan-A, D2-40, h-caldesmon, smooth muscle actin, and smooth muscle myosin. In contrast, calponin was negative in all PACs and PENs. Staining for alpha-inhibin was absent in PACs and present in 4.1% of PENs; whereas immunoreactivity for m-NSE was present in 26.8% of PACs and 73.7% of PENs. Chromogranin staining was present in 9.1% of PACs and 100% of PENs. An immunohistochemical profile of staining with calponin, alpha-inhibin, and m-NSE and absent staining with chromogranin supports the diagnosis of SMA, and distinguishes SMA from PAC and PEN. Calponin and alpha-inhibin are the most useful positive markers for SMA, and are negative in most entities in the differential diagnosis.