Dome-Type Carcinoma of the Ascending Colon: A Case Report

Abstract

Background: Dome-type carcinoma (DC) is a rare clinical entity first described by De Petris et al in 1999 followed by Jass et al in 2000. The tumor is described as a focus of adenocarcinoma contained within dense lymphoid stroma associated with dome type epithelium. Herein we report the endoscopic and pathologic findings in an additional case of DC in order to add to the limited number of documented cases. Case Presentation: An asymptomatic 78 year old male with a prior personal history of four tubular adenomas was found to have three broad-based polyps on routine surveillance colonoscopy. Pathology showed prominent lymphoid aggregates with nests of invasive adenocarcinoma that were well to moderately differentiated and contained no goblet cells. The findings were confined to the superficial submucosa. The final pathologic features were consistent with the typical appearance of dome-type carcinoma. The patient subsequently underwent an uncomplicated right hemicolectomy with an uneventful post-operative recovery. Conclusion: DC is a distinct variant of colorectal carcinoma with dense lymphoid component but devoid of microsatellite instability or EBV infection. The tumor is felt to arise from M cells associated with the follicle-associated epithelium of gut-associated lymphoid tissue within the colon. This assumption comes from the lack of goblet cells and the association with lymphoid tissue. Nearly all cases are low grade with excellent prognosis without recurrence. To our knowledge our reported case appears to be the only case found in a patient without abdominal complaints or a family history of colorectal carcinoma, as most patients have one or both findings. Through this case report we hope to bring further attention to this distinct clinical entity while adding another case to the current body of literature.Figure 1Figure 2Figure 3