This finding may suggest that mutation is not closely associated with the carcinogenesis of this MiNEN. Immunohistochemical analysis with an anti-BCL10 antibody was very useful for detecting the BPH-715 aggressive component of this tumor by identifying the pancreatic differentiation of acinar cells in the tumor. both components of this tumor showed no genomic mutation and BPH-715 a low methylation epigenotype, the rate of recurrence of AI was higher in the acinar-endocrine component than in the adenocarcinomatous component. The getting of AI indicated the progression of the conventional adenocarcinoma to an acinar-endocrine component and recognized the aggressive potential of the acinar-endocrine component. Conclusions We statement a rare case of gastric MiNEN with pancreatic acinar differentiation. AI analysis exposed tumor progression and aggressiveness. In addition, the usefulness of the anti-BCL10 antibody for detecting the acinar-endocrine component was suggested. monoclonal antibody, polyclonal antibody, bad, positive, ready-to-use The immunohistochemical results are summarized in Table?1. Cells dissection and DNA extraction DNA from each component was extracted from stereoscopically dissected paraffin-embedded cells sliced up at a 10-m thickness, and including more than 60% of tumor cells, with TaKaRa DEXPAT (TAKARA Bio Inc., Japan) according to the manufacturers instructions. Mutation analysis of the and genes The gene (exons 5 to 8) was analyzed with polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis followed by PCR direct sequencing as explained previously [8]. No mutation was found in either of the tumor parts. Microsatellite analysis Allelic imbalance (AI) was examined to determine the aggressiveness of the solid component having a PCR-microsatellite assay (GeneAmp PCR System 9600; Perkin-Elmer, CA, USA) relating to previously reported methods [7]. AI on chromosomes 1p, 5q, 8p, 11, 18p and 22q was examined with 27 highly pleomorphic microsatellite markers often associated with AI in GCs, shown in Table?2. The results of the AI analysis will also be demonstrated in Table?2. Although AI was recognized on chromosomes 5q, 8p, 11q and 22q in the solid component, AI was recognized only on chromosome 11q in the glandular component (Figs.?3a-i). Table 2 Results of allelic imbalance analyses not informative, heterozygosity, loss of heterozygosity Open in a separate windowpane Fig. 3 Representative results of allelic DNMT1 imbalance analysis. a-c Consecutive hematoxylin and eosin (H&E)-stained specimen of the cells sampled for DNA extraction. a Non-neoplastic mucosa sampled for d and g, b Glandular tumor component sampled for e and h, and c Acinar-endocrine component sampled for f and i. d-f The alleles at D8S532. e and f display loss of heterozygosity (LOH) (black arrows). g-i The alleles at D11S5014. h showed heterozygosity, but i showed LOH (black arrow) DNA methylation analysis DNA methylation status was classified as low, intermediate or high, having a two-step method [9]. The cutoff value was more than 30% of the tumor. In this case, the DNA methylation status of each component was determined to be a low methylation epigenotype. Conversation and conclusions Gastric MiNEN is an BPH-715 uncommon tumor, and gastric MiNEN with pancreatic acinar differentiation is extremely rare. The present GC was composed of standard adenocarcinomatous and solid-acinar differentiated parts. Although NEN is generally diagnosed by immunohistochemical manifestation of at least two of three markers, chromogranin A, synaptophysin and CD56, the solid component of the present tumor was positive only for chromogranin A, and showed faint manifestation of synaptophysin that was regarded as bad. Different general markers for identifying neuroendocrine differentiation are used in different organs [10]. In the gastrointestinal tract, chromogranins and/or synaptophysin are used [11]. In addition, the definition of pancreatic neuroendocrine carcinoma from the WHO classification is definitely described relative to markers of neuroendocrine differentiation as diffuse or faint synaptophysin and faint or focal chromogranin A staining [12]. Consequently, the solid component with pancreatic acinar differentiation can be considered as an endocrine carcinoma component. To the best of our knowledge, only four instances of GC with ductal, endocrine and pancreatic acinar differentiation have been reported to day [5, 6]. Although one of the four.