BackgroundHER2 is overexpressed and amplified in approximately 15% of invasive breast cancers, and is the molecular target and predictive marker of response to anti-HER2 agents. In a subset of these cases, heterogeneous distribution of HER2 gene amplification can be found, which creates clinically challenging scenarios. Currently, breast cancers with HER2 amplification/overexpression in just over 10% of cancer cells are considered HER2-positive for clinical purposes; however, it is unclear as to whether the HER2-negative components of such tumors would be driven by distinct genetic alterations. Here we sought to characterize the pathologic and genetic features of the HER2-positive and HER2-negative components of breast cancers with heterogeneous HER2 gene amplification and to define the repertoire of potential driver genetic alterations in the HER2-negative components of these cases.ResultsWe separately analyzed the HER2-negative and HER2-positive components of 12 HER2 heterogeneous breast cancers using gene copy number profiling and massively parallel sequencing, and identified potential driver genetic alterations restricted to the HER2-negative cells in each case. In vitro experiments provided functional evidence to suggest that BRF2 and DSN1 overexpression/amplification, and the HER2 I767M mutation may be alterations that compensate for the lack of HER2 amplification in the HER2-negative components of HER2 heterogeneous breast cancers.ConclusionsOur results indicate that even driver genetic alterations, such as HER2 gene amplification, can be heterogeneously distributed within a cancer, and that the HER2-negative components are likely driven by genetic alterations not present in the HER2-positive components, including BRF2 and DSN1 amplification and HER2 somatic mutations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-015-0657-6) contains supplementary material, which is available to authorized users.

Pancreatic heterotopia is rare. Patients with pancreatic ectopia diagnosed by pathological study, whether asymptomatic or with mild symptoms, should be observed. Lesions incidentally detected during surgeries need to be removed by conservative procedures.

Clinical variables had no influence on the patients' prognosis. Among the macroscopic variables, the form of the neoplasia and its involvement in the intestinal circumference did influence the patients' prognosis. These last two variables are important data capable of contributing to the identification of patient subpopulations with greater or lesser prognostic risk.

This immunohistochemical method can be employed successfully in the detection of neoplastic cells in lymph nodes previously considered free. In this study, there was a trend towards lower survival in node-positive patients but this did not reach statistical significance.

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