Pseudomyxoma peritonei (PMP) is a rare malignant disease (1-2 cases per million per year) that most often originates from the appendix and presents as a mucinous adenocarcinoma growing in the peritoneal cavity. The abundance of mucinous ascites secreted by the more common low-grade (LG) subtype of PMP leads to progressive obstruction, which is eventually fatal. In addition to mucin production, the high-grade (HG) subtype of PMP is able to invade surrounding tissues and organs, thereby shortening the survival time when compared to the LG disease. We have analyzed the mutational profile of PMP and found KRAS mutation to be frequent and nearly always combined with mutated GNAS or other component of the cAMP-PKA signaling pathway. Further we have identified CEA and EpCAM proteins to be ubiquitously expressed in PMP cells, thus serving as immunohistochemistry markers to detect PMP cells. We have a representative series of over hundred formalin-fixed, paraffin-embedded (FFPE) PMP tissue specimens. In PMP research, we participate in the COST Action CA17101, European Network on Pseudomyxoma Peritonei.
Defects in mismatch repair genes lead to microsatellite instable (MSI) colorectal cancer (CRC), which accounts for approximately 15% of all CRC cases. Clinically it is important to recognize MSI status, which is the basis of tumor grading (WHO, IARC Press, 2010), has an effect on prognosis and, in certain cases, directs adjuvant drug treatment of the patients. We have a large CRC series of nearly five hundred FFPE specimens of which we have analyzed both MSI and BRAF V600E mutation status.