BACKGROUND: Herein we report a case of an extremely rare pancreatic adenocarcinoma with enteroblastic differentiation (AED), an underrecognized histological subtype. Moreover, the tumor was mixed with a neuroendocrine carcinoma (NEC), which is also a rare malignancy in the pancreas.
METHODS: The patient was an elderly male who was incidentally diagnosed with a 35 mm-sized pancreatic head tumor and underwent pancreatoduodenectomy. Histopathologically, the tumor was composed of four different types: conventional ductal adenocarcinoma, AED, NEC, and squamous cell carcinoma. Interestingly, p53 overexpression and loss of Rb expression, which are characteristic findings of NEC, were observed in all components. He had been received adjuvant chemotherapy after the surgery, however, he died of bath-related cardiac arrest 14 months after surgery.
CONCLUSIONS: In the stomach, AED, a carcinoma resembling fetal gut epithelium, is a rare but established subtype and is considered a related entity of hepatoid carcinoma (HAC). However, gastric AED and HAC differ to some extent. In contrast to the stomach, extragastric AED, including pancreatic AED, is extremely rare, and its biological features are unclear. A mixed tumor with NEC is a complex phenomenon, but it is occasionally reported in extragastric AED. The histogenesis of mixed AED-NEC can be resolved by determining p53 and Rb status.
CONCLUSIONS: Owing to their rare and novel nature, extragastric AED is under-recognized or confused with HAC. Further studies and the establishment of an extragastric AED classification are required.

Adenocarcinoma with enteroblastic differentiation is a rare histologic subtype of adenocarcinoma of the gastrointestinal tract that shows unique histologic and immunohistochemical features that resemble fetal intestinal epithelium. This histological subtype has been widely described in the stomach, where it most frequently appears, but, in other locations, it is misdiagnosed because of the poor experience in routine diagnostic setting. Here we present a case of an 87-year-old male with an adenocarcinoma of the ampulla of Vater with enteroblastic differentiation with a literature review of the cases described of this subtype in this location to date. The anatomical peculiarity of the ampulla, joined with the infrequent nature of this histological subtype, makes this case of great interest to aid to better characterize the biological behavior of these tumors.

Gastric adenocarcinoma with enteroblastic differentiation is a specific subtype of gastric cancer that is rare and highly malignant, usually presenting at an early stage with lymphovascular invasion, lymph node, and distant metastases, resulting in a poor prognosis. The pathology of this patient showed a classic tubular adenocarcinoma infiltrating into the mucosal layer, with the presence of cytoplasmic translucent tumor cells below the mucosal layer. It is noteworthy that this patient did not exhibit lymphovascular invasion, lymph node, and distant metastasis. Additionally, a large amount of calcification was observed; therefore, it remains unclear whether there exists any correlation between the two factors. To the best of our knowledge, this is the first case report demonstrating massive calcification in gastric adenocarcinoma with enteroblastic differentiation, which may have implications for future diagnosis of this rare subtype of gastric cancer.

Adenocarcinoma with enteroblastic differentiation is an extremely rare tumor with poor prognosis and unique pathologic features. The tumor appears to be relatively more common in stomach, with rare cases reported in esophagus, colon, rectum and ampulla. Underrecognition by pathologists may be a contributing factor towards underreporting of this tumor. Combination of carcinosarcoma and enteroblastic differentiation has not been reported so far.We report a unique case of ampullary carcinosarcoma with enteroblastic differentiation in a 59-year-old female, diagnosed in the pancreatoduodenectomy specimen. The carcinomatous component showed features of enteroblastic differentiation characterized by tubular architecture with clear cytoplasm, solid component with trabecular architecture and immunohistochemical expression of SALL4 and AFP. The patient was treated with adjuvant Folfirinox chemotherapy and is disease free at 17 months follow up.

In addition to hepatoid adenocarcinoma (HAC), gastric adenocarcinoma with enteroblastic differentiation (GAED) and common adenocarcinoma (COM) could also show hepatoid differentiation, which presents a poor prognosis. To elucidate the histogenesis and development of gastric cancer with hepatoid differentiation, we identified 55 cases by histological morphology and a panel of markers, including α-fetoprotein (AFP), Glypican 3 (GPC3) and SALL4, then clinicopathological parameters, pathomorphological characteristics, mucin phenotypes, molecular features, Immunoscore and survival analysis were assessed. A mixture of three types (COM + GAED + HAC) was most commonly observed in the same case, and typical transitions between each histological subtype were frequently seen. Hyaline globule and pink amorphous substance were often present. HER2 was amplified in 21.8% of cases. All the tumors showed intestinal phenotype (69.1%) and mixed gastric/intestinal phenotype (30.9%) and were all defined to chromosomal instable (CIN)/genomically stable (GS) group. Considering that 83.6% cases presented TP53 gene mutation phenotype and 61.8% cases showed ≥10% aberrant E-cadherin expression, the precise molecule classification is ambiguous. Survival analysis showed that patients with high SALL4 expression, high preoperative serum AFP level, or low Immunoscore had a significantly poor overall survival (OS). Moreover, SALL4, HER2, and Immunoscore had an independent influence on OS. In conclusion, we suggest that the development of gastric adenocarcinoma with hepatoid differentiation might a continuously progressive profile: from intestinal-type COM adenocarcinoma to GAED and then HAC. CIN/GS subtypes might be where they belonged. SALL4, HER2, and Immunoscore may be potential therapeutic targets.

Gastric adenocarcinoma with enteroblastic differentiation (GAED) is rare, highly malignant, and has higher vascular invasion and metastasis rates than conventional differentiated gastric cancer (CDGC). We report two cases of GAED that underwent curative resection by endoscopic submucosal dissection (ESD). Case 1 was an 82-year-old man with an elevated lesion in the gastric cardia. Biopsy revealed well-differentiated tubular adenocarcinoma. Pathological diagnosis of the ESD specimen revealed intramucosal gastric cancer without lymphovascular invasion (LVI). Although the surface layer of the lesion showed well and moderately differentiated tubular adenocarcinoma, clear cytoplasmic cancer cells positive for Sal-like protein-4 (SALL4) and Glypican-3 were found in a part of the deep layer. Therefore, GAED was diagnosed as present in a part of the whole lesion and covered with CDGC. Case 2 was an 83-year-old man with an elevated lesion in the gastric angulus. Biopsy revealed papillary and well-differentiated tubular adenocarcinomas. Pathological diagnosis of the ESD specimen revealed intramucosal gastric cancer without LVI. The entire lesion was occupied by papillary and tubular cancer cells, and had clear vesicles. Pure GAED was diagnosed, because the cells were SALL4 positive. In both cases, resection was curative despite the difference in pathological features.

Objective: To study the proportion and clinicopathological characteristics of gastric adenocarcinoma with enteroblastic differentiation (GAED) in gastric cancers showing an elevated serum alpha fetoprotein(AFP). Methods: A total of 724 resected gastric adenocarcinomas were collected from 2008 to 2018 at the 904 Hospital of Joint Service Support Force, and cases with pre-operative serum AFP>10 μg/L were screened. From the cases with elevated serum AFP, GAED cases were further evaluated based on morphology. Then the clincopathological features and immunohistochemical phenotypes of GAED were reviewed. In addition, the amplification of HER2 gene was detected with fluorescence in situ hybridization(FISH). When overall survival (OS) and progression-free survival (PFS) of GAED were analyzed, 289 cases ordinary gastric adenocarcinoma with normal serum AFP were employed as a control. Results: The percentage of GAED was 44% (11/25) in gastric cancers with elevated serum AFP. GAED was histologically tubular or papillary with clear cytoplasm, and some GAED cases showed cystadenoid structure similar to embryo sac (5 cases), homogeneous eosinophilic granules (4 cases) and intragland ulareosinophilic material (6 cases). All 11 GAED cases had lymph node metastasis. Liver metastasis and vascular thrombus were observed in 2 cases and 5 cases respectively. GAED was immunohistochemically positive for CDX2 (11/11), CD10 (8/11) and MUC2(3/11), which were intestinal epithelium differentiation markers. Meanwhile, primitive markers SALL4 (8/11), GPC3 (7/11) and AFP (5/11) were also expressed in GAED, and HER2 gene amplification was found in 3 cases (3/11) of GAED. Lastly, the PFS of GAED were significantly shorter than that of the control group (P=0.02), while OS was not statistically different between these two groups (P=0.99). Conclusions: Patients with GAED usually have a higher rate of elevated serum AFP in gastric adenocarcinoma, and the cancer exhibites features of both intestinal and primitive differentiation. As GAED is highly invasive, the prognosis of GAED may be poor. For GAED, the diagnosis of well-differentiated or moderately-differentiated adenocarcinoma should be avoided, because this diagnosis leads to underestimated malignant potential.
目的： 探讨血清甲胎蛋白（AFP）升高的胃癌病例中伴有肠母细胞分化的胃腺癌（GAED）所占比例及其临床病理特征。 方法： 收集2008至2018年解放军联勤保障部队第九○四医院胃癌手术切除标本共724例，以术前血清AFP>10 μg/L为标准，筛选血清AFP升高的胃癌病例，在此基础上按病理学标准筛选GAED病例，进一步观测其形态病理学特征，并采用免疫组织化学染色检测其分化表型，荧光原位杂交（FISH）检测HER2扩增情况。以289例不伴有AFP升高的普通胃腺癌作为对照组，比较GAED与对照组在无进展生存期和总体生存期上的差异。 结果： 724例胃腺癌中，伴血清AFP升高者有25例，其中GAED有11例，占44%。镜下观察：11例GAED以管状乳头状结构为主，胞质透明或空泡状，其中5例可见囊腺样结构，类似于胚胎发育时的胚囊；4例可见均质红染的圆形颗粒；6例可见腺腔内红染物。所有11例GAED均有淋巴结转移，同时2例有肝转移，5例可见血管内癌栓。癌细胞表达肠型分化标志物CDX2（11/11）、CD10（8/11）、MUC2（3/11）和原始分化标志物SALL4（8/11）、GPC3（7/11）、AFP（5/11）。同时有3例GAED存在HER2基因扩增（3/11）。随访显示，11例GAED的无进展生存期较对照组明显更短（P=0.02），而总体生存期则差异无统计学意义（P=0.99）。 结论： 导致血清AFP升高的胃癌中GAED占有较高比例，此类胃癌兼有肠型分化和原始的低分化特点，其侵袭转移能力强，预后可能较差，应避免将其诊断为普通高-中分化腺癌而低估其恶性程度。.

A 70-year-old man underwent endoscopy, which revealed a slightly depressed and elevated gastric cancer with suspected submucosal invasion of the mid gastric body. Biopsy specimens revealed differentiated tubular adenocarcinoma. We also detected lung and esophageal cancer and prioritized treatment of these lesions, and the patient underwent three endoscopies to monitor changes in gastric cancer. The tumor size and color remained unchanged; however, the marginal ridge was prominent, and the depressed area was deeper on subsequent evaluation. Total gastrectomy was performed 9 months after the first endoscopy. Histopathological examination of the resected specimens showed muscularis propria invasion, well-differentiated tubular adenocarcinoma involving the superficial mucosa, and tumor cells showing clear cytoplasm and a columnar or three-dimensional structure, between the deep mucosa and submucosa. The cells were immunopositive for Sal-like protein 4 and glypican 3; therefore, the patient was diagnosed with gastric adenocarcinoma with enteroblastic differentiation (GAED). This rare gastric cancer variant constituted approximately 70% of the entire lesion, and we observed significant lymphovascular invasion and lymph node metastasis. GAED is a rare histopathological subtype of gastric cancer described in recent years. Few cases of this tumor are reported to date; therefore, our study significantly contributes to the literature.

Adenocarcinoma with enteroblastic differentiation (ACED) has high malignant potential. It is known as clear-cell adenocarcinoma, which is a special type of adenocarcinomas characterized by primitive intestine-like structures. Although ACED is often encountered in the stomach, it is very rare in the colon and has not been sufficiently reported. ACED has also not been described in the WHO and Japanese Colonic Carcinoma Classification. ACED has biological characteristics of easy metastasis and a poor prognosis than these of tubular adenocarcinoma. Therefore, all cases of colonic ACED that have been reported previously required either surgery or chemotherapy. We describe a case of flat-elevated-type and 15 mm in size colonic ACED that was successfully treated with endoscopic submucosal dissection. We report our case along with a relevant literature review.

Gastric adenocarcinoma with enteroblastic differentiation (GAED) is a very rare variant of alpha-fetoprotein-producing gastric cancer (AFPGC). GAED is histologically characterized by cuboidal or columnar cells, which resemble those found in the primitive gut and have clear cytoplasm. In previously reported cases, GAED exhibit more aggressive behavior, as well as AFPGC, than conventional gastric cancer, such as marked lymphovascular invasion, lymph node metastasis, and liver metastasis. And also GAED was usually located in a deep mucosal layer and was covered by a conventional adenocarcinoma (CA) component. Based on these findings, GAED is considered to develop from CA during the process of tumor invasion and proliferation. We present a very rare case of early-stage GAED achieved curatively resected via endoscopic submucosal dissection, in which the lesion was composed of a pure enteroblastic differentiation component without a CA component.