Mixed adenoneuroendocrine carcinoma of gastrointestinal tract: Report of two cases

Abstract

Mixed adenoneuroendocrine carcinoma (MANEC) is a rare tumor of the gastrointestinal tract that consists of a dual adenocarcinomatous and neuroendocrine differentiation, each component representing at least 30% of the tumor. To date, only seven cases have been reported in the cecum, and less than 40 in the stomach. Our first case was diagnosed in a 74-years-old female as a polypoid lesion of the cecum with direct invasion in the transverse colon, without lymph node metastases. The second case was diagnosed in the stomach of a 46-years-old male as a polypoid tumor of the antral region that invaded the pancreas and presented metastases in 22 regional lymph nodes. The metastatic tissue was represented by the glandular component. In both cases, the tumor consisted of a moderately-differentiated tubular adenocarcinoma (with mucinous component in Case 1) intermingled with neuroendocrine carcinoma. Ki67 index was lower than 20% in Case 1, respectively higher than 20% in Case 2. The neuroendocrine component was marked by synaptophysin and neuron specific enolase, being negative for Keratins 7/20. The neuroendocrine component represented 60% in Case 1, and 40% in Case 2, respectively. The glandular components were marked by carcinoembryonic antigen, maspin and keratin 20/7 (Case 1/2). Both cases were proved to be microsatellite stable. Independently by the localization and tumor stage, MANECs appear to be highly malignant tumors, with high risk for distant metastases. The aggressiveness seems to depend on the endocrine component, independent of its proportion. The neuroendocrine component could be a dedifferentiated adenocarcinoma with a neuroendocrine phenotype.

Mixed adenoneuroendocrine carcinoma (MANEC) of the gastroesophageal junction: a case report and review of the literature

“…The two (6)(7)(8). Diagnosis is mainly based on the neoplasm architecture, completed by the immunostains with specific neuroendocrine markers (chromogranin, synaptophysin, CD56 or nueuron-specific enolase) combined with the markers on non-endocrine differentiation (9). To date, the optimal management strategy is unknown and no therapeutic strategies are recommended, although it seems reasonable to take into account the more aggressive component of MANECs (10).…”

A Rare Type of Colorectal Cancer: Mixed Adeno-Neuroendocrine Carcinoma (MANEC)

“…The origin of these tumours is still not clear (5,6,7). MANECs are thought to arise from multi-potential stem cells which have differentiated bidirectionally (8) or from dedifferentiated adenocarcinomas with a neuroendocrine phenotype (7).…”

Mixed adenoneuroendocrine carcinoma of the ampulla of Vater: A case report

“…In general, MANECs are highly aggressive tumour types with a high risk for distant metastasis, and prognosis is often dismal. It is largely unclear whether the glandular or the neuroendocrine component is the major driving force of disease progression and thus crucial for metastatic cancer spread (11,20,21).…”