AUTHOR=Koelzer Viktor H., Steuer Karl, Gross Ulrike Camenisch, Zimmermann Dieter, Paasinen-Sohns Aino, Mertz Kirsten D., Cathomas Gieri TITLE=Colorectal Choriocarcinoma in a Patient with Probable Lynch Syndrome JOURNAL=Frontiers in Oncology VOLUME=6 YEAR=2016 URL=https://www.frontiersin.org/articles/10.3389/fonc.2016.00252 DOI=10.3389/fonc.2016.00252 ISSN=2234-943X ABSTRACT=BackgroundPersonalized therapy of colorectal cancer is influenced by morphological, molecular, and host-related factors. Here, we report the comprehensive clinicopathological and molecular analysis of an extra-gestational colorectal choriocarcinoma in a patient with probable Lynch syndrome.Case presentationA 61-year-old female with history of gastric cancer at age 36 presented with a transmurally invasive tumor of the right hemicolon and liver metastasis. A right hemicolectomy was performed. Histopathological analysis showed a mixed trophoblastic and syncytiotrophoblastic differentiation, consistent with choriocarcinoma. Disease progression was rapid under oxaliplatin, capecitabine, irinotecan, and bevacizumab. Molecular phenotyping identified loss of mismatch-repair protein immunostaining for PMS2, microsatellite instability, a lack of MLH1 promoter methylation, and lack of BRAF mutation suggestive of Lynch syndrome. Targeted next-generation sequencing revealed an ataxia telangiectasia mutated (p.P604S) missense mutation. A bleomycin, etoposide, and cisplatin treatment protocol targeting germ cell neoplasia lead to disease remission and prolonged survival of 34 months.ConclusionComprehensive immunohistochemical and genetic testing is essential to identify uncommon cancers possibly related to Lynch syndrome. For rare tumors, personalized therapeutic approaches should take both molecular and morphological information into account.