De Gregorio Michael (Orcid ID: 0000-0003-2441-7495) Page 1 of 8 Metastatic sigmoid colon adenocarcinoma and tumour-related sarcoid reaction: A case report and literature review Michael De Gregorio 1 , Andrew J. Brett 2 1 Department of General Medicine, Royal Melbourne Hospital, Victoria, Australia 2 Department of Gastroenterology and Hepatology, Royal Melbourne Hospital, Victoria, Australia Main Text Introduction The association between malignancy and tumour-related sarcoid reaction is well-documented, characterised by the formation of non-caseating granulomas within tumour stroma, regional lymph nodes and non-regional tissues. It is recognised in both haematological and solid malignancies, with increasing case reports in non-metastatic and metastatic colon cancer. The clinical significance of tumour-related sarcoid reaction remains unclear, with contradicting and inconsistent data likely reflecting a complex immuno-pathophysiological response in a heterogeneous group. We herein present a case report of a thirty-two-year old female diagnosed with concurrent metastatic sigmoid colon adenocarcinoma and pulmonary granulomatous disease suggestive of a tumour-related sarcoid reaction. This article is protected by copyright. All rights reserved. This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/imj.13812