DOME/GALT type adenocarcimoma of the colon: a case report, literature review and a unified phenotypic categorization

Rare Case of Gut-associated Lymphoid Tissue Carcinoma in the Sigmoid Colon of a Very Elderly Patient: A Case Report

Colorectal cancer with gut-associated lymphoid tissue (GALT) carcinoma histopathology is particularly rare in very elderly patients. GALT is characterized by submucosal localization and prominent lymphoid infiltration with germinal center formation within tumor-infiltrating lymphocytes. This study aims to report a case of colorectal cancer with GALT carcinoma histopathology in a very elderly patient and to provide a comprehensive literature review. In this case, a 90-year-old female presented with an irregularly elevated tumor in the sigmoid colon, diagnosed via colonoscopy. Computed tomography revealed no lymph node or distant metastases. The patient underwent laparoscopy-assisted sigmoid colon resection with D3 dissection. Histopathological examination revealed well-differentiated adenocarcinoma in the submucosal layer with partial invasion into the muscle layer. Lymphocytes, along with lymph follicles, proliferated compressively in the stroma surrounding the tumor glands. Immunohistochemical analysis showed lost expression of mismatch repair proteins, MLH1 and PMS2, consistent with the tumor immunohistochemistry profile. B cells (CD20- and CD79a-positive) were generally distributed in and around the lymph follicles, while T cells (CD3-positive) were primarily located between the lymph follicles. This case highlights the rare histopathology of GALT carcinoma in colorectal cancer and underscores the importance of considering such diagnoses in elderly patients with colorectal tumors.

Gut-associated Lymphoid Tissue/Dome-Type Carcinoma of the Colon: A Rare Case Report With Review of the Literature

Gut-associated lymphoid tissue (GALT) carcinoma, also termed dome-type carcinoma, is an infrequent distinctive subtype of colorectal adenocarcinoma and only 18 cases have been reported in the English medical literature. These tumors have unique clinicopathological features and are considered to have a low malignant potential with favorable prognosis. Herein, we described a case of a 49-year-old male with intermittent hematochezia for 2 years. Colonoscopy revealed a sessile broad-based polyp of approximately 20 mm × 17 mm in the sigmoid colon 260 mm away from the anus, with a slightly hyperemic surface. Histologically, this lesion showed typical GALT carcinoma. The patient was followed up for one and a half year and he did not experience any discomfort, such as abdominal pain or hematochezia, and no tumor recurrence occurred. Moreover, we reviewed the literature, summarized the clinicopathological features of GALT carcinoma, and highlighted its pathological differential diagnosis to further explore this infrequent type of colorectal adenocarcinoma.

Dome-type carcinoma of the rectum mimicking a submucosal tumor: a case report and literature review

Dome-type carcinoma (DC) has been recognized as a rare variant of adenocarcinoma, which arises in gut-associated lymphoid tissue. It has a specific morphologic feature of a dome-like protrusion associated with lymphoid tissue. We report a case of a DC of the rectum in an asymptomatic 58-year-old male. A 2-cm sized, well-demarcated, round mass masquerading as a submucosal tumor (SMT) was identified in the rectum and was resected by endoscopic submucosal dissection. The tumor was revealed as an adenocarcinoma with submucosal invasion of 3,700 µm, which consisted of dilated cystic glands and the lymphoid stroma with reactive germinal centers. On immunohistochemistry, the tumor cells revealed retained expression for mismatch repair proteins. Laparoscopic surgical resection was subsequently performed. DC is considered a distinctive subtype of colorectal adenocarcinoma with characteristic morphology and low-grade malignant potential. Careful detection of the overlying mucosal lesion is crucial to differentially diagnose DC from SMT.

Whole exome sequencing of a gut-associated lymphoid tissue neoplasm points to precursor or early form of sporadic colon carcinoma

Gut-associated lymphoid tissue (GALT) carcinoma is a colorectal neoplasm characterized by cystically dilated neoplastic glands that extend into prominent, well-circumscribed submucosal lymphoid tissue. Although often subtle, lamina propria between and around the neoplastic glands (identified by plasma cells, scattered eosinophils, etc.) is frequent in cases with classic morphology, arguing (at least in such cases) in favor of adenoma extending into lymphoglandular complexes rather than true invasive carcinoma. Some have postulated that the tumor arises from M-cells, specialized epithelial cells overlying GALT, and others have suggested it represents a unique pathway to carcinoma, specific to the environmental conditions of epithelium overlying lymphoid tissue. Although both hypotheses are intriguing, definitive phenotypic and genetic support is currently lacking. To address these possibilities, we undertook whole exome sequencing and immunohistochemical characterization of a GALT neoplasm recently identified on our clinical service. We discovered well-known mutations in both APC and KRAS, as well as mutations in several Wnt pathway components (MED12, BCL9L, RFX4, DACT3). No immunohistochemical expression of GP2, a marker of M-cell differentiation, was identified. Expression of CDX2, SATB2, and the DNA mismatch repair proteins was observed, while expression of both CK7 and CK20 was absent. No PD-L1 expression was present on tumor cells, but PD-L1 expression was noted in a subset of tumor-adjacent mononuclear cells. Overall, the findings suggest that GALT neoplasms, although morphologically distinct, may be a precursor or early form of typical sporadic colon carcinoma.

Colorectal epithelial neoplasm associated with gut-associated lymphoid tissue

BACKGROUND

Colorectal epithelial neoplasm extending into the submucosal gut-associated lymphoid tissue (GALT) can cause difficulties in the differential diagnosis. Regarding GALT-associated epithelial neoplasms, a few studies favor the term "GALT carcinoma" while other studies have mentioned the term "GALT-associated pseudoinvasion/epithelial misplacement (PEM)".

METHODS

The clinicopathologic characteristics of 11 cases of colorectal epithelial neoplasm associated with submucosal GALT diagnosed via endoscopic submucosal dissection were studied.

RESULTS

Eight cases (72.7%) were in males. The median age was 59 years, and age ranged from 53 to 73. All cases had a submucosal tumor component more compatible with GALT-associated PEM. Eight cases (72.7%) were located in the right colon. Ten cases (90.9%) had a non-protruding endoscopic appearance. Nine cases (81.8%) showed continuity between the submucosal and surface adenomatous components. Nine cases showed (81.8%) focal defects or discontinuation of the muscularis mucosae adjacent to the submucosal GALT. No case showed hemosiderin deposits in the submucosa or desmoplastic reaction. No case showed single tumor cells or small clusters of tumor cells in the submucosal GALT. Seven cases (63.6%) showed goblet cells in the submucosa. No cases showed oncocytic columnar cells lining submucosal glands.

CONCLUSIONS

Our experience suggests that pathologists should be aware of the differential diagnosis of GALT-associated submucosal extension by colorectal adenomatous neoplasm. Further studies are needed to validate classification of GALT-associated epithelial neoplasms.

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

AIM

To present a comprehensive review of the etiology, clinical features, macroscopic and pathological findings, and clinical significance of Gut-associated lymphoid tissue or “dome” carcinoma of the colon.

METHODS

The English language medical literature on gut- or gastrointestinal-associated lymphoid tissue (GALT) or “dome” carcinoma of the colon was searched and appraised.

RESULTS

GALT/dome-type carcinomas of the colon are thought to arise from the M-cells of the lymphoglandular complex of the intestine. They are typically asymptomatic and have a characteristic endoscopic plaque- or “dome”-like appearance. Although the histology of GALT/dome-type carcinomas displays some variability, they are characterized by submucosal localization, a prominent lymphoid infiltrate with germinal center formation, tumor-infiltrating lymphocytes, absence of desmoplasia, and dilated glands lined by columnar epithelial cells with bland nuclear features and cytoplasmic eosinophilia. None of the patients reported in the literature with follow-up have developed metastatic disease or local recurrence.

CONCLUSION

Increased awareness amongst histopathologists of this variant of colorectal adenocarcinoma is likely to lead to the recognition of more cases.

GALT carcinoma: three case reports with glycoprotein 2 immunohistochemistry and electron microscopic observations

AIMS

Gut-associated lymphoid tissue (GALT) carcinoma is a rare colorectal tumour that arises in the epithelium covering GALT. GALT carcinoma is a differentiated tubular adenocarcinoma with dense lymphoid tissue with a characteristically well-demarcated margin. To date, 26 cases of GALT carcinoma, including the three cases discussed here, have been reported. Most (24 of 26) were discovered at early stages and none of the cases have documented any metastases. This suggests that GALT carcinoma may have a favourable prognosis. It is hypothesised that GALT carcinoma originates from M cells in specialised epithelia covering GALT. However, this hypothesis has yet to be confirmed.

METHODS AND RESULTS

In this study, we examined three cases of GALT carcinoma by immunohistochemistry detection of glycoprotein 2, a specific marker for M cells, and electron microscopy. Our findings showed that the tumour cells of GALT carcinoma in all three cases were negative for M cells. We thus concluded that GALT carcinoma may be a tubular adenocarcinoma arising by chance in the GALT. This unique carcinoma is a diferentiated adenocarcinoma that grows slowly with the development of GALT.

CONCLUSIONS

We propose that GALT carcinoma should be classified separately because of its histological setting and good prognosis.

The third pathway of colorectal carcinogenesis

Aims

The majority of the colorectal carcinomas (CRC) arise in a vast mucosal area built with columnar cells and mucus-producing goblet cells. These carcinomas evolve via the conventional (tubular/villous) adenoma–carcinoma pathway, or the serrated adenoma–carcinoma pathway. Much less frequently CRC arise in the gut-associated lymphoid tissue (GALT) mucosal domain via the third pathway of colorectal carcinogenesis.

Methods

All publications on human colorectal GALT carcinomas in the literature were reviewed.

Results

Only 23 GALT-carcinomas found in 20 patients are in record. The GALT carcinomas were detected at surveillance colonoscopic biopsy in 11 patients (four had ulcerative colitis, two were members of a Lynch syndrome family, two of a CRC family, one had familial adenomatous polyposis (FAP), one prior colon adenomas and one a submucosal tumour), or at diagnostic colonoscopic biopsy in the remaining nine patients (three had rectal bleedings, two abdominal pains, one diverticular disease and one protracted constipation. In three, no ground disease or symptoms were provided). In six of the 23 GALT carcinomas, the luminal surface showed tumour cells, ulcerations or no descriptions were given. Ten (66.7%) of the remaining 15 GALT carcinomas showed on top, adenomas (n=8) or high-grade dysplasia (n=2).

Conclusions

The low frequency of GALT carcinomas might be explained by the fact that the colorectal mucosal areas occupied by GALT domains are minute. The finding that two-thirds of the 15 remaining GALT carcinomas (vide supra) were covered by high-grade dysplasia or by conventional adenomas strongly suggest that conventional non-invasive neoplasias might have preceded the majority of the GALT carcinomas in record.

First reports of esophageal adenocarcinoma with white globe appearance in Japanese and Caucasian patients

Background and study aims: Better endoscopic diagnosis in case of Barrett's esophagus is still needed. White globe appearance (WGA) is a novel endoscopic marker for gastric adenocarcinoma, with high sensitivity for differentiating between gastric cancer/high-grade dysplasia and other lesions. We report 2 cases of esophageal adenocarcinoma with WGA. In Case 1, esophagogastroduodenoscopy (EGD) revealed a 10-mm esophageal adenocarcinoma in a 48-year-old Japanese woman with short-segment Barrett's esophagus. A small (< 1 mm) white globular lesion, typical of WGA, was observed under the epithelium by magnifying narrow-band imaging. A dilated neoplastic gland with eosinophilic material and necrotic epithelial fragments was identified at the site of the WGA by histologic examination. In Case 2, EGD revealed a 5-mm esophageal adenocarcinoma in a 60-year-old Caucasian man with long-segment Barrett's esophagus. A typical WGA was observed by magnifying narrow-band imaging and similar histologic findings were identified at the site of the WGA. WGA could be a reliable endoscopic finding for target biopsy in esophageal adenocarcinoma, if its specificity is as high as in gastric cancer. The clinical implications of WGA in patients with Barrett's esophagus should be investigated further.