Composite neuroendocrine tumor and adenocarcinoma of the rectum

Clinicopathological characteristics of co-existing or mixed colorectal cancer and neuroendocrine tumor: Report of five cases

Coexisting or mixed type of colorectal tumors has been rarely reported. This study was designed to investigate clinicopathological characteristics of co-existing or mixed colorectal adenocarcinoma and highly differentiated neuroendocrine tumor (NET-G1). To do that, clinicopathological characteristics of five cases of co-existing or mixed colorectal adenocarcinoma and NET-G1 admitted to our institution between 2017 and 2021 were retrospectively analyzed and literature review was conducted. Four patients were male and one female, aged 62-75 years old. Among them, four cases were diagnosed with rectal cancer and one case of colon cancer. Gross examination found that one patient was diagnosed with multiple colon polyps including three malignant polyps, and the remaining four cases of ulcerous masses. The tumors infiltrated into the muscle layer in two cases, and three cases with tumors infiltrating into surrounding adipose tissues. Microscopic examination revealed one patient developed poorly differentiated adenocarcinoma and four cases of moderately differentiated adenocarcinoma. Four patients had adenocarcinoma and NET-G1 in colon, and one case of adenocarcinoma in colon and NET-G1 in appendix. To conclude, co-existing or mixed colorectal tumors are extremely rare in clinical settings. Clinicopathological characteristics of five cases of co-existing or mixed adenocarcinoma and NET-G1 are diverse and adenocarcinoma is more aggressive in most affected patients.

Digestive MiNENs: Could histological classification and molecular characterization drive clinical outcome and therapeutic approach?

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are epithelial neoplasms in which neuroendocrine and non-neuroendocrine discrete components are combined, each of which constitutes ≥ 30% of the neoplasm. The finding of an additional neuroendocrine component seems to characterize the tumor's biological behavior. Few studies have proved MiNENs histogenetic and molecular characterization, and the development of molecular markers for more accurate classification of MiNENs represents a clinical need. However, a common origin of the neuroendocrine and non-neuroendocrine components from a pluripotent cancer stem cell could be suggested. The optimal clinical management of MiNENS is largely unknown. Whenever feasible, curative-intent resection should be performed for localized disease; in advanced disease, the treatment should be targeted to the component responsible for the metastatic spreading. This paper provides a revision of the current knowledge on MiNENs, focusing on available evidence about their molecular characterization to suggest a prognostic stratification of these rare forms.

Mixed epithelial endocrine neoplasms of the colon and rectum – An evolution over time: A systematic review

BACKGROUND

Mixed tumors of the colon and rectum, composed of a combination of epithelial and endocrine elements of benign and malignant potential are rare neoplasms. These can occur anywhere in the gastrointestinal tract and are often diagnosed incidentally. Though they have been a well-documented entity in the pancreas, where the exocrine-endocrine mixed tumors have been known for a while, recognition and accurate diagnosis of these tumors in the colon and rectum, to date, remains a challenge. This is further compounded by the different terminologies that have been attributed to these lesions over the years adding to increased confusion and misclassification. Therefore, dedicated literature reviews of these lesions in the colon and rectum are inconsistent and are predominantly limited to case reports and case series of limited case numbers. Though, most of these tumors are high grade and of advanced stage, intermediate and low grade lesions of these mixed tumors are also increasingly been reported. There are no established independent consensus based guidelines for the therapeutic patient management of these unique lesions.

AIM

To provide a comprehensive targeted literature review of these complex mixed tumors in the colon and rectum that chronicles the evolution over time with summarization of historical perspectives of terminology and to further our understanding regarding their pathogenesis including genomic landscape, clinicoradiological features, pathology, treatment, prognosis, the current status of the management of the primary lesions, their recurrences and metastases.

METHODS

A comprehensive review of the published English literature was conducted using the search engines PubMed, MEDLINE and GOOGLE scholar. The following search terms [“mixed tumors colon” OR mixed endocrine/neuroendocrine tumor/neoplasm/lesion colon OR adenocarcinoma and endocrine/neuroendocrine tumor colon OR mixed adenocarcinoma and endocrine/neuroendocrine carcinoma colon OR Amphicrine tumors OR Collision tumors] were used. Eligibility criteria were defined and all potential relevant items, including full articles and/or abstracts were independently reviewed, assessed and agreed upon items were selected for in-depth analysis.

RESULTS

In total 237 full articles/abstracts documents were considered for eligibility of which 45 articles were illegible resulting in a total of 192 articles that were assessed for eligibility of which 139 have been selected for reference in this current review. This seminal manuscript is a one stop article that provides a detailed outlook on the evolution over time with summarization of historical perspectives, nomenclature, clinicoradiological features, pathology, treatment, prognosis and the current status of the management of both the primary lesions, their recurrences and metastases. Gaps in knowledge have also been identified and discussed. An important outcome of this manuscript is the justified proposal for a new, simple, clinically relevant, non-ambiguous terminology for these lesions to be referred to as mixed epithelial endocrine neoplasms (MEENs).

CONCLUSION

MEEN of the colon and rectum are poorly understood rare entities that encompass an extensive range of heterogeneous tumors with a wide variety of combinations leading to tumors of high, intermediate or low grade malignant potential. This proposed new revised terminology of MEEN will solve the biggest hurdle of confusion and misclassification that plagues these rare unique colorectal neoplasms thus facilitating the future design of multi institutional prospective randomized controlled clinical trials to develop and evaluate newer therapeutic strategies that are recommended for continued improved understanding and personal optimization of clinical management of these unique colorectal neoplasms.

Synchronous Triple Gastric Cancer Incorporating Mixed Adenocarcinoma and Neuroendocrine Tumor Completely Resected with Endoscopic Submucosal Dissection

The endoscopic and pathological features of early gastric mixed adenoneuroendocrine carcinoma (MANEC), as well as its carcinogenesis, remain largely unclear. Screening esophagogastroduodenoscopy was performed on an 80-year-old man, revealing 3 superficial elevated lesions. Endoscopic submucosal dissection (ESD) was performed, and the patient was diagnosed with intramucosal gastric cancer comprising mixed adenocarcinoma and neuroendocrine tumor, well-differentiated adenocarcinoma and well-differentiated adenocarcinoma, with negative margins. To our knowledge, this is the first report describing the endoscopic and pathological findings of synchronous triple gastric cancer incorporating mixed adenocarcinoma and neuroendocrine tumor completely resected with ESD.