Is medullary carcinoma of the colon underdiagnosed? An audit of poorly differentiated colorectal carcinomas in a large national health service teaching hospital

Medullary carcinomas of the nonampullary small intestine: association with coeliac disease, mismatch repair deficiency, PD-L1 expression, and favourable prognosis

AIM

Gastrointestinal medullary carcinoma is a rare histologic subtype of adenocarcinoma. As nonampullary small bowel medullary carcinomas (SB-MCs) are poorly characterized, we aimed to analyse their clinicopathologic and immunohistochemical features and to compare them with nonmedullary small bowel adenocarcinomas (NM-SBAs).

METHODS AND RESULTS

Surgically resected SBAs collected through the Small Bowel Cancer Italian Consortium were classified as SB-MCs (carcinomas with ≥50% of tumour fulfilling the typical histologic criteria of MC) or NM-SBAs. Immunohistochemistry for cytokeratin (CK)7, CK20, CDX2, programmed death-ligand 1 (PD-L1) and mismatch repair proteins was performed in both SB-MCs and NM-SBAs. SB-MCs were also tested for CK8/18, synaptophysin, SMARCB1, SMARCA2, SMARCA4, and ARID1A and for Epstein-Barr virus (EBV)-encoded RNAs by in-situ hybridization. MLH1 promoter methylation status was evaluated in MLH1-deficient cases. Eleven SB-MCs and 149 NM-SBAs were identified. One (9%) SB-MC was EBV-positive, while 10 (91%) harboured mismatch repair deficiency (dMMR). MLH1 promoter hypermethylation was found in all eight dMMR SB-MCs tested. Switch/sucrose nonfermentable deficiency was seen in two (18%) SB-MCs, both with isolated loss of ARID1A. Compared with NM-SBAs, SB-MCs exhibited an association with coeliac disease (P < 0.001), higher rates of dMMR (P < 0.001), and PD-L1 positivity by both tumour proportion score and combined positive score (P < 0.001 for both), and a lower rate of CK20 expression (P = 0.024). Survival analysis revealed a better prognosis of SB-MC patients compared to NM-SBA cases (P = 0.02).

CONCLUSION

SB-MCs represent a distinct histologic subtype, with peculiar features compared to NM-SBAs, including association with coeliac disease, dMMR, PD-L1 expression, and better prognosis.

Emerging and under-recognised patterns of colorectal carcinoma morphologies: a comprehensive review

While the overwhelming majority of colorectal carcinomas (CRC) are diagnosed as adenocarcinoma not otherwise specified, there are numerous under-recognised morphologic patterns of CRC. These patterns are recognised by the WHO, appear in reporting manuals for the American Joint Committee of Cancer, and/or are listed on synoptic reports, while many other variants have either fallen out of favour or are emerging as future bona fide patterns. Herein, we discuss 13 variants: serrated adenocarcinoma, micropapillary adenocarcinoma, medullary carcinoma, neuroendocrine carcinoma, mucinous adenocarcinoma, signet-ring cell carcinoma, adenosquamous carcinoma, adenoma-like adenocarcinoma, lymphoglandular complex-like CRC, carcinoma with sarcomatoid components, cribriform-comedo-type adenocarcinoma, undifferentiated carcinoma and low-grade tubuloglandular adenocarcinoma. The purpose of this review is to scrutinise these variants by assessing their clinical characteristics, morphologic cues, as well as pitfalls, and address their prognostic significance. Our analysis aims to bring clarity and updated understanding to these variants, offering valuable insights for pathologists. This contributes to more nuanced CRC diagnosis and treatment strategies, highlighting the importance of recognising a broad spectrum of morphologic patterns in CRC.

Predictive Values of Homeobox Gene A-Antisense Transcript 3 (HOXA-AS3), Cystatin 6 (CST6), and Chromobox Homolog 4 (CBX4) Expressions in Cancer Tissues for Recurrence of Early Colon Cancer After Surgery

Purpose

We aim to explore the predictive values of homeobox gene A-antisense transcript 3 (HOXA-AS3), cystatin 6 (CST6), and chromobox homolog 4 (CBX4) expressions in cancer tissues for the recurrence of early colon cancer after surgery.

Patients and Methods

A total of 136 patients who received surgery from January 2020 to January 2021 were enrolled and followed up for 24 months to observe the recurrence after surgery, based on which they were assigned into recurrence and non-recurrence groups. All patients underwent a histopathological examination on admission.

Results

The recurrence group had a lower degree of differentiation as well as a higher HOXA-AS3 level and CST6 and CBX4 expression scores than those of the non-recurrence group (P<0.05). HOXA-AS3 level, CST6 expression score, and CBX4 expression score were risk factors for the recurrence of early colon cancer after surgery [odds ratio (OR)>1, P<0.05]. The receiver operating characteristic curve analysis showed that the areas under the curves of HOXA-AS3 level, CST6 expression score, CBX4 expression score, and their combination for predicting recurrence were 0.909 [95% confidence interval (95% CI): 0.785-1.000], 0.819 (95% CI: 0.690-0.948), 0.794 (95% CI: 0.663-0.926), and 0.942 (95% CI: 0.882-1.000), respectively.

Conclusion

The expressions of HOXA-AS3, CST6, and CBX4 in cancer tissues have close correlations with the recurrence of early colon cancer after surgery and are thus of high predictive values.

Invasive stratified mucin-producing carcinoma of the colorectum: expanding the morphologic spectrum of large bowel cancer

BACKGROUND

Invasive stratified mucin-producing carcinoma is a recently recognized adenocarcinoma with distinctive features. It was first described in the cervix but similar tumors have since been reported in the penis, anus and prostate. In the gastrointestinal tract, the phenomenon of epithelial stratification has an interesting embryologic morphogenesis. Gastrointestinal mucosa starts off as nascent columnar epithelium that is subsequently patterned to confer regional specific functions. However, in disease states, normal architectural patterning can be disrupted by aberrant differentiation. Given this background and the phenotypic plasticity of neoplastic cells, we were interested in ascertaining whether invasive stratified mucin-producing carcinoma occurs in the colorectum.

METHODS

This was a retrospective study of all 584 cases of colorectal carcinoma accessioned at our institution over a 2-year period (January 2021- December 2022). Cases were analyzed to determine which fulfilled the criteria for invasive stratified mucin-producing carcinoma.

RESULTS

There were 9 cases of colorectal invasive stratified mucin-producing carcinoma-one pure form and 8 mixed. They showed the classic colorectal (CK20 + , CDX2 + , CK7-) immunostaining profile but, based on various morphologic criteria, they could be distinguished from conventional adenocarcinoma NOS, mucinous, signet ring cell, medullary, goblet cell and undifferentiated carcinomas. About half the cases were MLH1/PMS2 deficient and BRAF &/or PIK3CA mutated, which aligns with the hypermutated phenotype.

CONCLUSIONS

Colorectal invasive stratified mucin-producing carcinoma appears to be a real entity, best recognized in its early stages. It appears to be a high-grade carcinoma. With tumor progression, it evolves into a mucinous adenocarcinoma with a proclivity towards signet ring cells. In summary, the study of this tumor, particularly in its early stages, provides useful clues to further understanding the biology and progression of large bowel cancer. Further studies are required to learn more about this tumor.

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.

Medullary carcinoma of the colon: A comprehensive analysis of the National Cancer Database

PURPOSE

Medullary carcinomas (MC) of the colon are uncommon tumors. In this study, we analyzed demographic and disease characteristics as well as survival outcomes of MC versus undifferentiated (UDA) and poorly differentiated (PDA) adenocarcinomas (AC) of the colon.

MATERIALS AND METHODS

The National Cancer Database (2004-2018) was utilized to identify patients with colon cancer. Patient demographics (including age, gender, race), disease characteristics (including grade, TNM stage, carcinoembryonic levels, perineural and lymphovascular invasion, lymph node status, microsatellite stability, KRAS mutation, and primary tumor site), and facility type and location were evaluated. Chi-square tests were used to compare descriptive data. Cox Regression and Kaplan Meier analyses were used to analyze survival characteristics.

RESULTS

1,041,753 patients with colon cancer were identified of whom 2709 patients had MC and 897,902 had AC (136,597 PDA and 18,042 UDA). MC was seen in older patients (mean age 74 ± 13 years) and women (72.5% vs. 27.5% males). Most MCs were poorly differentiated (63.3%), and 82.4% of patients with MC had microsatellite instability. Fewer patients with MC had perineural invasion (15.6% vs. 22.0% in PDA and 22.4% in UDA, p < 0.001) and positive lymph nodes (38.4% versus 59.9% with PDA and 59.7% with UDA, p < 0.0001). MC diagnosis increased by year (Cochran-Armitage trend test, p < 0.0001). Kaplan Meir analysis revealed a better prognosis for patients with MC when compared to PDA or UDA (p < 0.001).

CONCLUSION

Given the rarity, pathologists should maintain a high suspicion for MC when encountering poorly differentiated or undifferentiated right-sided colon cancer with associated MSI-H.

Colorectal medullary carcinoma: heterogeneous presentations of a rare clinico-pathological entity. Report of two cases

Colorectal medullary carcinoma (CMC) is a rare subset of minimally differentiated carcinomas. CMC tend to be right-sided and present at an advanced stage. Despite this, distant metastases are rare at presentation. The liver and the regional lymph nodes represent the most common sites of metastases. Most of the time, CMCs exhibit mismatch repair deficiency and a strong association with high-level microsatellite instability. There is no conspicuous data regarding treatment strategies and short-term outcomes. CMC is supposed to be related to better prognosis compared to poorly-differentiated and undifferentiated colonic adenocarcinomas, but reports are controversial.This lesion, with heterogeneous presentations and unclear prognostic significance, may be unfamiliar to histopathologists and can lead to diagnostic uncertainty and overtreatments.Our aim is to renew the attention to this rare histological subtype through the report of two cases.

Clinical and Molecular Characteristics of Rare Malignant Tumors of Colon and Rectum

Simple Summary

Tumors of colon and rectum other than adenocarcinomas represent a neglected issue from clinical and laboratory points of view because of their rarity. In this review, we summarize and describe the rare histologic entities occurring in colon and rectum. Clinical and pathologic characteristics, prognostic behavior, treatments, and altered genes are reported to provide readers with a paramount and comparative perspective. In relation to this, we propose that improvements in registries and multidisciplinary research are warranted to ameliorate their management.

Abstract

The most frequent form of colorectal cancer is represented by adenocarcinoma being about 98% of tumor histological types. However, other rare histotypes can be found in colon and rectum (adenosquamous, goblet cell adenocarcinoma, lymphoma, medullary carcinoma, melanoma, mesenchymal, neuroendocrine, plasmacytoma, signet ring, squamous tumors). Altogether, these forms account for less than 2% of colorectal tumors. There are no specific diagnostic or therapeutic recommended approaches and most of the information available from literature derives from small and retrospective clinical series. In the present study, we provide a paramount and updated view on clinical and biologic characteristics of rare colorectal tumors.

Medullary Carcinoma of the Gastrointestinal Tract: Report on Two Cases with Immunohistochemical and Molecular Features

Medullary carcinoma of the colon is a rare histological variant characterized by a poorly differentiated morphology, an aberrant immunophenotype, and microsatellite instability. Despite the lack of glandular differentiation, medullary carcinoma is reported to have a good prognosis. It is typically located in the right colon and frequently affects older women. Due to its clinical, histological, biological, and genetic peculiarity, medullary carcinoma requires an accurate diagnosis and the awareness of this diagnostic possibility. We describe the morphological, immunohistochemical, and molecular findings of two interesting cases, the first one in the right colon of a patient and the second one in the terminal ileum of a patient with Crohn's disease. Deeper knowledge of all the biological and clinical features will allow appropriate and specific treatment of this tumor in the future.