Gut-associated lymphoid tissue or so-called “dome” carcinoma of the colon: Review

ARTICLE HIGHLIGHTS

Research background

Carcinomas that are accompanied by a lymphoid component are a well- recognized entity in several topographic sites. In the gastrointestinal tract, dome or gut- or gastrointestinal-associated lymphoid tissue (GALT) carcinoma (GALT/dome-type carcinoma) is a rare, enigmatic form of gastrointestinal cancer. Current classifications of gastrointestinal tract cancers do not recognize GALT/dome-type carcinoma as a distinct histological subtype, although these lesions do demonstrate distinctive histological and clinical characteristics. This is a comprehensive review of the etiology, clinical features, macroscopic and pathological findings, and clinical significance of this entity. A diagnosis of GALT/dome-type carcinoma should be considered by pathologists when a well-circumscribed, submucosal lesion composed of cystic dilated glands containing eosinophilic material, lined by a single layer of non-mucinous, eosinophilic epithelium, accompanied a conspicuous lymphoid component replete with germinal centers and tumor-infiltrating lymphocytes, is seen.

Research motivation

Comprehensive clinical and pathological reviews of GALT/dome-type carcinoma are lacking. With this in mind, the key topics covered included the etiology, clinical features, macroscopic and pathological findings, and clinical significance of GALT/dome-type carcinoma. The authors reviewed the published literature to provide evidence to address the following questions: Why are GALT/dome-type carcinomas so rare? Do GALT/dome-type carcinomas actually exist? What is the etiology of GALT/dome-type carcinomas? Are GALT/dome-type carcinomas a separate category distinct from conventional adenocarcinomas? There is considerable evidence summarized herein that supports the theory that GALT/dome-type carcinoma is a distinct histological subtype, as these lesions do demonstrate distinctive histological and clinical characteristics. Increased awareness of this entity amongst pathologists and clinicians will enable the correct diagnosis and thus facilitate the accumulation of cases and phenotypic characterization, which may establish GALT/dome-type carcinoma as a distinct subtype of colorectal adenocarcinoma in the future.

Research objectives

The objective was to search and appraise the English language medical literature on GALT or “dome” carcinoma of the colon. The pertinent etiology, clinical features, macroscopic and pathological findings, and clinical significance of GALT/dome-type carcinoma are presented herein. The authors provide evidence garnered from the literature to address the following pressing questions: Why are GALT/dome-type carcinomas so rare? Do GALT/dome-type carcinomas actually exist? What is the etiology of GALT/dome-type carcinomas? Are GALT/dome-type carcinomas a separate category distinct from conventional adenocarcinomas? It has been shown that GALT/dome-type carcinomas do demonstrate distinctive histological and clinical characteristics, and as such, should be considered a distinct histological subtype. Increased awareness of this entity amongst pathologists and clinicians will enable the correct diagnosis and thus facilitate the accumulation of cases and further characterization, which may confirm GALT/dome-type carcinoma as a distinct subtype of colorectal adenocarcinoma in the future.

Research methods

The English language medical literature on GALT or “dome” carcinoma of the colon was searched and appraised, using recognized search engines, PubMed and Google, with the keywords: “gut-associated lymphoid tissue”; “gastrointestinal-associated lymphoid tissue”; “GALT carcinoma”; “dome carcinoma”; “colon”. Cases of GALT or “dome” carcinoma of the colon have been reported as single case reports and as small case series in the English language medical literature. The relevant literature was thoroughly reviewed and appraised.

Research results

Based on the published literature, GALT/dome-type carcinomas do demonstrate distinctive etiological, histological and clinical characteristics. The number of published cases is small, however, and additional cases should be identified to enable further interrogation, which may provide even more robust evidence to firmly establish GALT/dome-type carcinoma as a distinct subtype of colorectal adenocarcinoma in the future.

Research conclusions

The pertinent etiology, clinical features, macroscopic and pathological findings, and clinical significance of GALT/dome-type carcinoma are presented herein. The published literature provides evidence that GALT/dome-type carcinomas do indeed demonstrate distinctive etiological, histological and clinical characteristics. Published evidence explaining the rarity and etiology of GALT/dome-type carcinomas is summarized. Published evidence supporting the concept that GALT/dome-type carcinomas actually exist is explored. Overall, the literature supports the designation of GALT/dome-type carcinoma as a separate category distinct from conventional adenocarcinomas. The key histological and clinical characteristics of GALT/dome-type carcinoma are emphasized to increase awareness amongst clinicians and pathologists. Additional cases should be identified to enable further interrogation, which may provide even more robust evidence to firmly establish GALT/dome-type carcinoma as a distinct subtype of colorectal adenocarcinoma in the future.

Research perspectives

Evidence suggests that GALT/dome-type carcinoma is indeed a separate entity distinct from conventional adenocarcinoma. However, additional cases are required to enable further interrogation of larger numbers of cases to confirm this theory. Awareness amongst histopathologists of the diagnostic criteria to render a diagnosis is essential to facilitate the identification and collection of additional cases.