Grading of PNETs by the highest Ki-67 index in EUS-FNA specimens with adequate cellularity has a high concordance with grading of resected specimens, and can predict long term patient survival with high accuracy.

Patients with pancreatic neuroendocrine neoplasm grade-3 (PanNEN-G3) show variable responses to platinum-based chemotherapy. Recent studies indicated that PanNEN-G3 includes well-differentiated neuroendocrine tumor with G3 (NET-G3). Here, we examined the clinicopathologic and molecular features of PanNEN-G3 and assessed the responsiveness to chemotherapy and survival. A total of 100 patients with PanNEN-G3 were collected from 31 institutions, and after central review characteristics of each histologic subtype [NET-G3 vs. pancreatic neuroendocrine carcinoma (NEC-G3)] were analyzed, including clinical, radiological, and molecular features. Factors that correlate with response to chemotherapy and survival were assessed. Seventy patients analyzed included 21 NETs-G3 (30%) and 49 NECs-G3 (70%). NET-G3 showed lower Ki67-labeling index (LI; median 28.5%), no abnormal Rb expression (0%), and no mutated (0%), whereas NEC-G3 showed higher Ki67-LI (median 80.0%), Rb loss (54.5%), and mutations (48.7%). Chemotherapy response rate (RR), platinum-based chemotherapy RR, and prognosis differed significantly between NET-G3 and NEC-G3. Chemotherapeutic outcomes were worse in NET-G3 ( < 0.001). When we stratified PanNEN-G3 with Rb and , PanNENs-G3 with Rb loss and those with mutated showed significantly higher RRs to platinum-based chemotherapy than those without (Rb loss, 80% vs. normal Rb, 24%, = 0.006; mutated, 77% versus wild type, 23%, = 0.023). Rb was a predictive marker of response to platinum-based chemotherapy even in NEC-G3 ( = 0.035). NET-G3 and NEC-G3 showed distinct clinicopathologic characteristics. Notably, NET-G3 does not respond to platinum-based chemotherapy. Rb and are promising predictors of response to platinum-based chemotherapy for PanNEN-G3, and Rb for NEC-G3..

EUS-FNA for pancreatic solid lesions yielded a high accuracy and low complication rate. Both cytological and cell-block preparations and on-site cytopathological evaluation contributed to improve the accuracy. The diagnostic ability of EUS-FNA was less for smaller lesions, and repeated procedures may be needed if malignancy is suspected.

EUS-TCB is a safe and accurate procedure for obtaining a histological diagnosis in patients with suspected AIP. EUS-TCB can serve as a rescue technique in cases of AIP lacking typical findings.

High-grade pancreatic intraepithelial neoplasia (HG-PanIN) is the major precursor of pancreatic ductal adenocarcinoma (PDAC) and is an ideal target for early detection. To characterize pure HG-PanIN, we analysed 23 isolated HG-PanIN lesions occurring in the absence of PDAC. Whole-exome sequencing of five of these HG-PanIN lesions revealed a median of 33 somatic mutations per lesion, with a total of 318 mutated genes. Targeted next-generation sequencing of 17 HG-PanIN lesions identified KRAS mutations in 94% of the lesions. CDKN2A alterations occurred in six HG-PanIN lesions, and RNF43 alterations in five. Mutations in TP53, GNAS, ARID1A, PIK3CA, and TGFBR2 were limited to one or two HG-PanINs. No non-synonymous mutations in SMAD4 were detected. Immunohistochemistry for p53 and SMAD4 proteins in 18 HG-PanINs confirmed the paucity of alterations in these genes, with aberrant p53 labelling noted only in three lesions, two of which were found to be wild type in sequencing analyses. Sixteen adjacent LG-PanIN lesions from ten patients were also sequenced using targeted sequencing. LG-PanIN harboured KRAS mutations in 94% of the lesions; mutations in CDKN2A, TP53, and SMAD4 were not identified. These results suggest that inactivation of TP53 and SMAD4 are late genetic alterations, predominantly occurring in invasive PDAC.

This study demonstrates a higher prevalence of likely independent co-occurring IPMN and ductal adenocarcinoma than previously appreciated. These findings have important implications for molecular risk stratification of patients with IPMN.

Purpose: Patients with mutations of epidermal growth factor receptor (EGFR) receive more benefit from EGFR-tyrosine kinase inhibitor treatment. However, usually such treatment is used to treat advanced lung cancer and only small biopsy samples are available for mutational analysis. We used immunohistochemistry to examine recently developed antibodies specific to major hotspot mutations of L858R and DEL E746-A750.Experimental Design: We used five series of lung cancers: 47 non-small cell lung cancers (NSCLC) to evaluate various types of EGFR mutations, a consecutive series of 238 NSCLCs to study the sensitivity and specificity, 11 NSCLCs with both EGFR mutation and amplification to examine the spatial distribution, 32 patients treated with gefitinib to compare clinical responses, and 15 NSCLCs to explore changes associated with acquired T790M mutation.Results: Each antibody specifically recognized the corresponding mutation but also recognized other types of mutations. Overall specificity and sensitivity were 96% and 47%, respectively. The positive reaction showed heterogeneous distribution that agreed with the expression of the total EGFR molecule, part of which was associated with gene amplification. A clinical response to gefitinib treatment correlated with the reaction, although one of the two patients with a positive reaction responded well despite having the wild-type EGFR. Acquired T790M mutation did not change the reaction to the antibodies.Conclusions: On some characteristics, the positive reaction to mutation-specific antibodies differs from the molecular EGFR mutation. Therefore, this study revealed that not all patients with EGFR mutations can be selected using these mutation-specific antibodies. Clin Cancer Res; 16(13); 3349-55. ©2010 AACR.

A new lung adenocarcinoma classification was recently proposed by IASLC/ATS/ERS. In this classification, invasive mucinous adenocarcinoma (IMC) is placed in a new category because of its unique radiologic, morphologic, and genetic characteristics. Minimal cytologic atypia characterizes this tumor; thus, it is occasionally difficult to make a diagnosis with a biopsy specimen. We used immunohistochemistry to examine HNF4α expression in a tissue microarray consisting of 278 lung adenocarcinoma specimens. In addition, we analyzed the clinicopathologic features, including EGFR, KRAS, and ALK mutation status. HNF4α expression was detected in 33 of the 37 surgically resected IMCs. The tumor cells were uniformly labeled with the molecule in all of the corresponding biopsy specimens, whereas the normal cells were not. Although HNF4α was also expressed in other lung adenocarcinoma subtypes, those with HNF4α expression shared IMC features, including negative TTF-1 expression (P<0.001), positive CDX2 expression (P<0.001), positive KRAS mutation status (P=0.001), and negative EGFR mutation status (P<0.001). Although some ALK-positive adenocarcinomas showed IMC morphology, the tumors were negative for HNF4α, suggesting that they belonged to a different group of tumors. We found that HNF4α labeled all of the IMC tumors except the ALK-positive adenocarcinomas. Thus, HNF4α positivity could serve as a useful marker for overcoming the diagnostic difficulties caused by minimal nuclear atypia and sparse tumor cells in small biopsy samples. Because other adenocarcinoma subtypes with HNF4α expression share clinicopathologic features with IMC, these adenocarcinomas, especially the columnar cell type of acinar-predominant adenocarcinoma, might constitute a biological spectrum of IMC.