Genetic basis of a common tumor origin in the development of pancreatic mixed acinar-neuroendocrine-ductal carcinoma: A case report

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.

Pancreatic Mixed Acinar-neuroendocrine-ductal Carcinoma: A Case Report and Literature Review

Pancreatic mixed neoplasms are very rare. We herein report a unique case of pancreatic mixed acinar-neuroendocrine-ductal carcinoma with trilineage differentiation. The patient was an 83-year-old woman referred to our hospital due to anemia and a pancreatic mass. Contrast-enhanced computed tomography revealed a 60-mm mass in the pancreas. Subtotal stomach-preserving pancreaticoduodenectomy was performed. The postoperative pathological diagnosis was mixed acinar-neuroendocrine-ductal carcinoma. Postoperative chemotherapy was conducted according to the adenocarcinoma and neuroendocrine carcinoma protocols. The patient died 26 months postoperatively. Choosing appropriate chemotherapy for mixed neoplasms is difficult. Cancer gene panel testing, if possible, may support the choice of therapeutic agents.

Mixed acinar-neuroendocrine carcinoma of the pancreas with positive for microsatellite instability: a case report and review of the literature

BACKGROUND

Mixed acinar-neuroendocrine carcinoma (MANEC) of the pancreas is a rare tumor. We report a case of successful surgical resection of expansively growing MANEC of the pancreas with microsatellite instability (MSI)-high.

CASE PRESENTATION

The patient was an asymptomatic 65-year-old male. A computed tomography (CT) scan for a follow-up after treatment of pneumonia incidentally revealed a hypoenhancing 12-cm expansively growing tumor in the pancreatic body. An endoscopic ultrasound-guided fine-needle aspiration of the tumor suggested the diagnosis of MANEC. We performed distal pancreatectomy with combined resection of the spleen, left adrenal gland, transverse colon, small bowel, and stomach. The intraoperative findings showed that the tumor was capsular and was in contact with the SMA, SMV, and CA; however, obvious infiltration of these vessels was not observed..Pathological findings indicated MANEC with MSI-high. Among mismatch repair (MMR) gene proteins, PMS2 was lost and MLH1, MSH2, and MSH6 were retained. The tumor recurred 5 months after surgery. The patient was treated with gemcitabine plus nab-paclitaxel followed by pembrolizumab, which did not show objective response.

DISCUSSION

This is the first report investigating MSI and MMR in MANEC. Standard chemotherapy has not been established for MANEC. Detection of MSI-high is essential since PD-1 monoclonal antibodies for MSI-high cases might be one of the good treatment options. Herein, we discuss the various cytomorphologic and clinical features of MANEC and present a brief review of the literatures.

CONCLUSIONS

The accumulation of data from additional cases is necessary to further evaluate this type of carcinoma and provide a standardized optimal therapy for MANEC.

Cells with stem-like properties are associated with the development of HPV18-positive cervical cancer

The cellular origins of cervical cancer and the histological differentiation of human papillomavirus (HPV)-infected cells remain unexplained. To gain new insights into the carcinogenesis and histological differentiation of HPV-associated cervical cancer, we focused on cervical cancer with mixed histological types. We conducted genomic and transcriptomic analyses of cervical cancers with mixed histological types. The commonality of the cellular origins of these cancers was inferred using phylogenetic analysis and by assessing the HPV integration sites. Carcinogenesis was estimated by analyzing human gene expression profiles in different histological types. Among 42 cervical cancers with known HPV types, mixed histological types were detected in four cases, and three of them were HPV18-positive. Phylogenetic analysis of these three cases revealed that the different histological types had a common cell of origin. Moreover, the HPV-derived transcriptome and HPV integration sites were common among different histological types, suggesting that HPV integration could occur before differentiation into each histological type. Human gene expression profiles indicated that HPV18-positive cancer retained immunologically cold components with stem cell properties. Mixed cervical cancer has a common cellular origin among different histological types, and progenitor cells with stem-like properties may be associated with the development of HPV18-positive cervical cancer.

Laser Capture Microdissection: A Gear for Pancreatic Cancer Research

The advancement in molecular techniques has been attributed to the quality and significance of cancer research. Pancreatic cancer (PC) is one of the rare cancers with aggressive behavior and a high mortality rate. The asymptomatic nature of the disease until its advanced stage has resulted in late diagnosis as well as poor prognosis. The heterogeneous character of PC has complicated cancer development and progression studies. The analysis of bulk tissues of the disease was insufficient to understand the disease, hence, the introduction of the single-cell separating technique aided researchers to decipher more about the specific cell population of tumors. This review gives an overview of the Laser Capture Microdissection (LCM) technique, one of the single-cell separation methods used in PC research.

PIK3CA-AKT pathway predominantly acts in developing ipsilateral breast tumor recurrence long after breast-conserving surgery

PURPOSE

Ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy is seen after a long interval, but the clinical classification of Residual Tumor Recurrence (RR) or Double Primary (DP) needs to be validated. We used genome profiling to identify the genetic alterations associated with IBTR.

METHODS

Among 1881 breast cancer patients treated with breast-conserving therapy between 1999 and 2018, IBTR occurred in 52 patients (2.8%). Of these 22 patients who consented for genomic analysis of Primary Breast Cancer (T1) and IBTR (T2) were studied. When the same gene mutations in T1 and T2 were identified, it was classified as genomic residual recurrence gRR, and when no shared mutations identified, it was classified as gDP. The differences between clinical and genomic classification were compared. Furthermore, the pathway of the genes which were responsible for recurrence was also examined.

RESULTS

Of 13 clinically diagnosed RRs (cRRs), 11 were gRR and 2 were gDPs, while of 9 cDPs, 6 were gDP and 3 gRR, with a match rate of 17/22 (77%). We searched for genes involved in IBTR: PIK3CA-AKT pathway mutations were found in 12 of 14 gRRs (86%) in T1, and only 2 of 8 gDPs (25%) with significant difference (p = 0.004). When both of PBC and IBTR compared, PIK3CA-AKT pathway abnormalities were 24/28 (86%) in the gRR and 5/16 (31%) in the gDP (p < 0.001).

CONCLUSIONS

Genome profiling revealed that abnormalities in the PIK3CA-AKT pathway in long-term residential recurrences and are a crucial molecular group in the development of IBTR.

The cytologic and immunohistochemical findings of pancreatic mixed acinar-endocrine carcinoma

BACKGROUND

The classification of epithelioid pancreatic neoplasms based on fine-needle aspiration (FNA) is important for proper management, as distinction of pancreatic neuroendocrine neoplasms from other similar appearing lesions can result in significantly different treatment. Mixed acinar-endocrine carcinomas (MAEC) are genetically related to acinar carcinomas and are treated as such. We reviewed cases of MAEC to better characterize their cytologic and immunohistochemical features.

METHODS

Eight FNAs of MAECs were identified and reviewed. A chart review for each case was conducted.

RESULTS

All patients were male, 42-68 years of age, and presented with either Stage 3 or 4 disease. Smear backgrounds of all cases showed naked nuclei without significant necrosis. The smears were cellular with cells arranged in either three-dimensional (3D) clusters with intervening capillaries or singly dispersed. Acinar formation was a prominent feature. Cells were round to oval with small to moderate amounts of delicate cytoplasm. The nuclei were round to oval with mild to moderate anisonucleosis with granular chromatin and small nucleoli. Apoptotic bodies and mitoses were noted in most cases, with Ki67 indices of 10%-48%. All tumors, by definition, demonstrated expression of trypsin and synaptophysin with variable chromogranin expression (50%).

CONCLUSION

The cytology of acinar cell carcinoma shares features with aspirates of other nonductal adenocarcinoma neoplasms of the pancreas. A clue to the diagnosis is that tumors show high Ki67 indices and a diagnosis of MAEC should be excluded anytime a diagnosis of Grade 2 or 3 well-differentiated neuroendocrine tumor or high-grade neuroendocrine carcinoma is in the differential.

Multi-regional sequencing reveals clonal and polyclonal seeding from primary tumor to metastases in advanced gastric cancer

BACKGROUND

Tumor metastases to lymph nodes and distant organs are associated with worse prognosis in gastric cancer. However, little is known about the genetic profiles, subclonal architecture, and evolutional processes across primary tumors and metastases.

METHODS

We analyzed the genetic alterations of 106 multiregional samples including primary tumors, lymph node metastases, and visceral metastases from 10 patients with advanced gastric cancer. Histologically different portions were obtained by laser-capture microdissection. We reconstructed the subclonal architectures and inferred the primary to lymph or visceral metastatic seeding patterns.

RESULTS

The different histological portions in primary tumors had common mutations, suggesting common ancestral tumor origins transformed into distinct histological types. In almost all cases, TP53 mutations were identified as clonal mutations across primary tumors and metastases. Subclonal reconstruction and phylogenetic analysis showed primary tumors were classified into monoclonal or polyclonal tumors. All monoclonal primary tumors disseminated as metastases with the same tumor composition (100%, 26/26 samples). In contrast, polyclonal primary tumors mainly spread as metastases by way of polyclonal seeding (84%: 37/44 samples).

CONCLUSIONS

Clonal mutations were maintained at both the primary and metastatic sites and genetic divergence of these was low. These findings shed light on the genetic basis of primary tumor dissemination and metastatic processes in advanced gastric cancer.

Accurate detection of KRAS, NRAS and BRAF mutations in metastatic colorectal cancers by bridged nucleic acid-clamp real-time PCR

BACKGROUND

Patients with metastatic colorectal cancer can benefit from anti-EGFR therapy, such as cetuximab and panitumumab. However, colorectal cancers harboring constitutive activating mutations in KRAS, NRAS and BRAF genes are not responsive to anti-EGFR therapy. To select patients for appropriate treatment, genetic testing of these three genes is routinely performed.

METHODS

We applied bridged nucleic acid-clamp real-time PCR (BNA-clamp PCR) to detect somatic hotspot mutations in KRAS, NRAS and BRAF. PCR products from BNA-clamp PCR were subsequently analyzed Sanger sequencing. We then compared results with those from the PCR-reverse sequence-specific oligonucleotide probe (PCR-rSSO) method, which has been used as in vitro diagnostic test in Japan. To validate the mutation status, we also performed next generation sequencing using all samples.

RESULTS

In 50 formalin-fixed paraffin-embedded tissues, KRAS mutations were detected at frequencies of 50% (25/50) and 52% (26/50) by PCR-rSSO and BNA-clamp PCR with Sanger sequencing, respectively, and NRAS mutations were detected at 12% (6/50) and 12% (6/50) by PCR-rSSO and BNA-clamp PCR with Sanger sequencing, respectively. The concordance rate for detection of KRAS and NRAS mutations between the two was 94% (47/50). However, there were three discordant results. We validated these three discordant and 47 concordant results by next generation sequencing. All mutations identified by BNA-clamp PCR with Sanger sequencing were also identified by next generation sequencing. BNA-clamp PCR detected BRAF mutations in 6% (3/50) of tumor samples.

CONCLUSIONS

Our results indicate that BNA-clamp PCR with Sanger sequencing detects somatic mutations in KRAS, NRAS and BRAF with high accuracy.

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

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

Relationship between formalin reagent and success rate of targeted sequencing analysis using formalin fixed paraffin embedded tissues

BACKGROUND

Tumor genetic alterations are determined to aid in selecting therapy and predicting prognosis. In routine clinical practice, targeted sequencing analysis is performed using formalin-fixed paraffin embedded (FFPE) tissues. However, successful genetic analysis remains challenging because FFPE DNA is fragmented during the sample preparation process.

METHODS

Real-time PCR was performed to assess DNA quality and quantities. Targeted sequencing was performed using FFPE tissues fixed with different types of formalin.

RESULTS

DNA was less fragmented from samples fixed in low formalin concentration (10% vs. 20%) and neutral buffered conditions (neutral buffered vs. non-neutral). DNA fragmentation increased over the fixation time. In a preliminary test study, we compared fixation using 10% neutral buffered formalin (n = 180) and 20% formalin (n = 26). The success rate of targeted analysis was higher using 10% neutral formalin (98.3%; 177/180) compared with 20% formalin (34.6%; 9/26). In a validation study with additional formalin-fixed paraffin embedded tissues fixed with 10% neutral buffered formalin (n = 860), we reproduced these results and achieved a high success rate for targeted sequencing analysis (98.4%; 846/860).

CONCLUSION

Our data show that 10% neutral buffered formalin is recommended for fixation of formalin-fixed paraffin embedded samples to achieve high success rate of targeted sequencing analysis.

Not only stem cells, but also mature cells, particularly neuroendocrine cells, may develop into tumours: time for a paradigm shift

Stem cells are considered the origin of neoplasms in general, and malignant tumours in particular, and the stage at which the stem cells stop their differentiation determines the degree of malignancy. However, there is increasing evidence supporting an alternative paradigm. Tumours may develop by dedifferentiation from mature cells able to proliferate. Studies of gastric carcinogenesis demonstrate that mature neuroendocrine (NE) cells upon long-term overstimulation may develop through stages of hyperplasia, dysplasia, and rather benign tumours, into highly malignant carcinomas. Dedifferentiation of cells may change the histological appearance and impede the identification of the cellular origin, as seen with gastric carcinomas, which in many cases are dedifferentiated neuroendocrine tumours. Finding the cell of origin is important to identify risk factors for cancer, prevent tumour development, and tailor treatment. In the present review, we focus not only on gastric tumours, but also evaluate the role of neuroendocrine cells in tumourigenesis in two other foregut-derived organs, the lungs and the pancreas, as well as in the midgut-derived small intestine.