Case Report
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 14, 2017; 23(6): 1106-1112
Published online Feb 14, 2017. doi: 10.3748/wjg.v23.i6.1106
Coexisting tubular adenoma with a neuroendocrine carcinoma of colon allowing early surgical intervention and implicating a shared stem cell origin
Mahmoud L Soliman, Ashish Tiwari, Qing Zhao
Mahmoud L Soliman, Qing Zhao, Department of Pathology and Laboratory Medicine, Boston University Medical Center, Boston, MA 02118, United States
Ashish Tiwari, Department of Gastroenterology, Boston University Medical Center, Boston, MA 02118, United States
Author contributions: Soliman ML and Zhao Q contributed to the acquisition of data, writing, and revision of this manuscript; Tiwari A provided the endoscopic picture in Figure 1 and wrote the figure legend; all authors have read and approved the final version of the manuscript for publication.
Institutional review board statement: This case report was exempt from the Institutional Review Board standards at Boston University
Informed consent statement: Consent was not obtained but the presented data are anonymized and risk of identification is minimal.
Conflict-of-interest statement: The authors declare no conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Qing Zhao, MD, PhD, Assistant Professor, Department of Pathology and Laboratory Medicine, Boston University Medical Center, 670 Albany Street, 6th floor, Room 670, Boston, MA 02118, United States.
Telephone: +1-617-4145339 Fax: +1-617-4145314
Received: October 28, 2016
Peer-review started: October 28, 2016
First decision: December 01, 2016
Revised: December 17, 2016
Accepted: January 4, 2017
Article in press: January 4, 2017
Published online: February 14, 2017

High-grade colonic neuroendocrine carcinomas (NECs) are uncommon but extremely aggressive. Their co-existence with tubular adenoma (TA) has rarely been reported. We present a 68-year-old man who was found on routine colonoscopy to have multiple colorectal TAs and an ulcerated lesion in the ascending colon. Microscopically, a poorly-differentiated invasive carcinoma juxtaposed with a TA was identified. Differential diagnosis included a poorly-differentiated adenocarcinoma, medullary carcinoma, high-grade NEC and lymphoma. The immunohistochemical profile showed positive staining for keratins, synaptophysin and chromogranin but negative for LCA, CDX2, CK7, CK20, TTF-1 and PSA, supporting the NEC diagnosis. Upon subsequent laparoscopic right hemicolectomy, the tumor was identified as a 3.0 cm umbilicated and ulcerated mass with an adjacent TA. Both TA and NEC showed positive staining for β-catenin indicating a shared colonic origin. The mitotic counts (77/10 high power fields) and a high proliferation rate (75% by Ki-67) corroborated a high-grade stratification. Mutational analysis indicated a wild-type BRAF and KRAS with mismatch repair proficiency. The AJCC (7th edition) pathologic stage is pT3, pN0, pMx. The patient received adjuvant chemotherapy with cisplatin/etoposides for three cycles and will be followed up for a year to detect recurrence. In conclusion, the co-existence of TA with high grade-NEC in our case allowed early identification and intervention of the otherwise asymptomatic but aggressive tumor. In addition, the finding of a high-grade NEC within a large TA in this case suggests a link between the two lesions and could represent a shared stem cell origin.

Keywords: Neuroendocrine carcinoma, Tubular adenoma, Colorectal, Colocalization

Core tip: This is a case report of a patient with a high-grade large cell neuroendocrine carcinoma in the ascending colon with an overlying tubular adenoma discovered during routine colonoscopic screening in absence of clinical symptoms. This is a unique case where the contiguity of the neuroendocrine carcinoma to the tubular adenoma allowed for the diagnosis of the otherwise asymptomatic high-grade carcinoma. Being aware of this association bears practical implication where it can be conducive to the early and correct diagnosis of invasive cancer. In addition, we review the literature citing pertinent cases.