Abstract
The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.
Highlights
The first description of a gastrointestinal tumor with an exocrine and a neuroendocrine component was published by Cordier in 1924 [1]
In addition to these mixed adenoneuroendocrine carcinomas (MANECs) types in which both components are histologically malignant, very rare tumors composed of adenoma and well differentiated neuroendocrine tumor (NET according to the nomenclature proposed by the 2010 WHO classification) have been described in the colon-rectum [9,10]
In the 2010 WHO classification of tumors of the digestive system, these mixed adenoma-Neuroendocrine Tumor (NET) neoplasms were not categorized [4]. Due to their low biological aggressiveness and their peculiar morphological features, we suggest using the term of mixed adenoneuroendocrine tumor (MANET) to diagnose these peculiar mixed neoplasms
Summary
The first description of a gastrointestinal tumor with an exocrine and a neuroendocrine component was published by Cordier in 1924 [1]. In amphicrine tumors exocrine and neuroendocrine features are present in the same neoplastic cell, which shows a divergent immunophenotype In addition to these MANEC types in which both components are histologically malignant, very rare tumors composed of adenoma and well differentiated neuroendocrine tumor (NET according to the nomenclature proposed by the 2010 WHO classification) have been described in the colon-rectum [9,10]. In the 2010 WHO classification of tumors of the digestive system, these mixed adenoma-NET neoplasms were not categorized [4] Due to their low biological aggressiveness and their peculiar morphological features, we suggest using the term of mixed adenoneuroendocrine tumor (MANET) to diagnose these peculiar mixed neoplasms.
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