J Cancer 2011; 2:302-306. doi:10.7150/jca.2.302 This volume

Case Report

Primary Mucinous Adenocarcinoma of the Vermiform Appendix with High Grade Microsatellite Instability

Moritz Komm1✉, Michaela Kronawitter-Fesl2, Marcus Kremer2, Ludwig Lutz3, Elke Holinski-Feder4, Reinhard Kopp1

1. Department of General Surgery, Klinikum München-Harlaching, Munich, Germany
2. Department of Pathology, Klinikum München-Harlaching, Munich, Germany
3. Department of Haematology and Oncology, Klinikum München-Harlaching, Munich, Germany
4. Medical Genetic Center, Munich, Germany

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Komm M, Kronawitter-Fesl M, Kremer M, Lutz L, Holinski-Feder E, Kopp R. Primary Mucinous Adenocarcinoma of the Vermiform Appendix with High Grade Microsatellite Instability. J Cancer 2011; 2:302-306. doi:10.7150/jca.2.302. Available from https://www.jcancer.org/v02p0302.htm

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Primary adenocarcinoma of the vermiform appendix is a rare entity and is frequently discovered by the pathologist following appendectomy for suspected appendicitis.

We present a 42-year-old male with primary mucinous adenocarcinoma of the appendix initially presenting symptoms of acute appendicitis. Histological investigation of the appendectomy specimen showed a mucinous adenocarcinoma and the patient was treated by secondary right hemicolectomy giving the final histopathological classification of an UICC IIIC tumor. Since the patient fulfills the revised Bethesda criteria analysis of immunoreactivity of DNA mismatch repair proteins was performed showing loss of MLH1 and MSH2 expression associated with high microsatellite instability (MSI-H), not yet reported for primary mucinous appendiceal carcinoma. Further genetic analysis for DNA mismatch repair gene mutations were negative. The patient received intensified adjuvant chemotherapy according to the FOLFOX-4-scheme, since MSI-H colorectal carcinomas might show lower response rates following standard 5-FU-based adjuvant chemotherapy.

Keywords: Appendixcarcinoma, microsatellite instability, mucinous appendixcarcinoma, DNA mismatch repair genes