LETTERS TO THE EDITOR

 

A case of a mixed adenoneuroendocrine tumor of the colon

 

 

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Key words: Mixed adenoneuroendocrine tumor.

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Dear Editor,

Neuroendocrine cells often coexist with exocrine neoplasms of the gut and each component is normally present in a variable range. Despite this frequent association, mixed exocrine-neuroendocrine carcinomas are rare (1). This entity is known as adenoneuroendocrine carcinoma (MANEC) and each of its malignant components represents at least 30% (2). In contrast, there are only a few reports of another rare association of an adenoma and a well differentiated neuroendocrine tumor (NET) in the colon and rectum (1-4). The term mixed adenoneuroendocrine tumor (MANET) was suggested due to its indolent behavior and distinct morphological characteristics with mild to moderate nuclear atypia and low number of mitoses (1). However, it is not included in the recent World Health Organization (WHO) classification of tumors of the digestive system (5).

 

Case report

We report the case of a 76-year-old male patient with a 60 mm type 0-Is lesion in the distal sigmoid colon identified by colonoscopy and removed by a piecemeal endoscopic mucosal resection. Histological examination revealed a mixed tumor phenotype. The lesions had a villous adenoma component with low-grade and focal high grade dysplasia and a well differentiated neuroendocrine component. No recurrence was observed during the endoscopic follow-up. Staging revealed no evidence of the tumor. The patient remains asymptomatic without evidence of recurrence after 24 months of follow-up.

 

Discussion

In this case, the tumor was limited to the mucosa and submucosa and was incidentally resected by EMR. These tumors have an excellent prognosis as no evidence of tumor recurrence was found in any previously reported cases (4).

Due to the histogenetic and nosologic problems associated with mixed colorectal neoplasms, the documentation of more cases of composite tumors of the large bowel would help to create a more complete morphologic spectrum of these tumors. The report of this unusual case contributes to the understanding of these rare tumor types.

 

 

Joana Ribeiro da Silva¹, Rolando Taveira Pinho¹ and Antónia Furtado²
Departments of ¹Gastroenterology and ²Pathology.
Centro Hospitalar Vila Nova de Gaia/Espinho.
Vila Nova de Gaia, Portugal

 

References

1. Nair M. Composite carcinoma of the colon: A case report with literature review. J Oncol 2007;5(2).         [ Links ]

2. Rosa SL, Marando A, Furlan D, et al. Colorectal poorly differentiated neuroendocrine carcinomas and mixed adenoneuroendocrine carcinomas: Insights into the diagnostic immunophenotype, assessment of methylation profile, and search for prognostic markers. Am J Surg Pathol 2012;36:601-11.         [ Links ]

3. Varghese NM, Zaitoun AM, Thomas SM, et al. Composite glandular-carcinoid tumour of the terminal ileum. J Clin Pathol 1994;47:427-9. DOI: 10.1136/jcp.47.5.427.         [ Links ]

4. Rosa S, Marando A, Sessa F, et al. Mixed adenoneuroendocrine carcinomas (MANECs) of the gastrointestinal tract: An update. Cancers 2012;4:11-30.         [ Links ]

5. Rindi G. Nomenclature and classification of neuroendocrine neoplasms of the digestive system. In: Bosman FT, Carneiro F, eds. WHO Classification of Tumours of the Digestive System. France: WHO; 2010. pp. 13-4.         [ Links ]