[Gastrointestinal stromal tumors of the stomach and precursor lesions]. / Gastrointestinale Stromatumoren des Magens und ihre Vorstufen.

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors in the gastrointestinal tract although they are much less frequent than epithelial tumors. In more than 60% of cases they occur in the stomach. Especially small lesions measuring ≤1 cm in diameter, so-called microscopic GIST can occur multifocally, frequently in the proximal stomach wall and sometimes as an incidental finding in a gastrectomy specimen resected for gastric cancer. The multicentricity of GIST alone is not proof of a metastatic behavior or a syndromal or hereditary disease. Multiple sporadic synchronous and metachronous GIST are characterized by different primary mutations mostly in the KIT or PDGFRA genes and are often less aggressive. It is speculative whether a field effect is responsible or whether still unknown GIST-promoting factors may facilitate the development of several independent lesions. If KIT or PDGFRA mutations are lacking, a succinate dehydrogenase (SDH) deficient GIST has to be considered, either hereditary as Carney-Stratakis syndrome or syndromal as part of a Carney triad.

[The change of pathology in the era of personalized medicine using the example of discordant KRAS mutational status in metastasized colorectal carcinoma]. / Der Wandel der Pathologie in der Ära der personalisierten Medizin. Eine Übersicht am Beispiel des diskordanten KRAS-Mutationsstatusbeim metastasierten kolorektalen Karzinom.

Modern pathology has developed from "omega" to "alpha" and is vital for therapy and follow-up of tumor treatment today. Pathology has a key role as part of personalized medicine. It is possible to intervene therapeutically into the molecular genetic intricacy of tumors by establishing predictive biomarkers with corresponding tumor therapeutic agents.By identifying the KRAS mutational status at the metastasized colorectal carcinoma, a statement about the benefit of an anti-EGFR-therapy can be given, which is nowadays the basis of diagnostic and therapy of this cancer.For a long period of time a high concordance between primary and metastases inside the KRAS status was taken for granted. Meanwhile, there are many studies demonstrating a possibly underestimated high degree of discordance. The identification of discordances might gather a subcollective, which partially holds a KRAS wild type tissue and thereby might respond with a partial remission. Thus, the survival time of these patients and their quality of living could be successfully improved.