title: Diffuse large B-cell lymphoma in colon confounded by prior history of colorectal cancer: A case report and literature review.
abstract: A 66-year-old male underwent left hemicolectomy for rectal adenocarcinoma in 2008. Five years later he was admitted to hospital with abdominal pain. A computed tomography scan revealed notable thickening of the middle of the ascending colon wall, and colonoscopy revealed an ulcerofungating mass of 3×3 cm in the cecum and extending to the ascending colon. Under the consideration of cancer recurrence, laparoscopic right hemicolectomy was performed directly. Surgical specimens revealed sheets of large pleomorphic lymphoid cells with nuclei of different sizes, nucleoli and mitotic phases visible in most cells. These tested positive for CD45, CD20 and CD79a diffusely, but negative for CD3, CD5, Bcl-2, Bcl-6 and ALK. The Ki-67 proliferation index was 40%. Epstein-Barr virusin situhybridization did not reveal any positive signals in any of the tumor cells. Based on these findings, the recurrent tumor was diagnosed as diffuse large B-cell lymphoma. The patient could have avoided surgery and received chemotherapy only; however, the case was confounded by the patient's prior history of colorectal cancer due to the rarity of colon lymphoma following rectal cancer in the same patient. It is therefore essential to investigate carefully and differentiate between potential lesions during routine postoperative colonoscopy following colorectal cancer surgery, as patients may present with rare colon lymphoma, which may be confused with a recurrence of colorectal cancer.
authors.affiliation: Department of Hematology, The First Affiliated Hospital of Zhejiang University, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Hematology, Tongde Hospital of Zhejiang, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Zhilu
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Hematology, Tongde Hospital of Zhejiang, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Chuanyong
authors.initials: C
authors.lastname: Su
authors.affiliation: Department of Hematology, The First Affiliated Hospital of Zhejiang University, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Tong
authors.affiliation: Department of Hematology, The First Affiliated Hospital of Zhejiang University, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Qian
keywords: colorectal cancer; diffuse large B-cell lymphoma; rectal adenocarcinoma; rituximab; second primary malignancy