Early gastric stump carcinoma with rhabdoid features. Case report

Unusual or Uncommon Histology of Gastric Cancer

This review comprehensively examines the diverse spectrum of gastric cancers, focusing on unusual or uncommon histology that presents significant diagnostic and therapeutic challenges. While the predominant form, tubular adenocarcinoma, is well-characterized, this review focuses on lesser-known variants, including papillary adenocarcinoma, micropapillary carcinoma, adenosquamous carcinoma, squamous cell carcinoma (SCC), hepatoid adenocarcinoma, gastric choriocarcinoma, gastric carcinoma with lymphoid stroma, carcinosarcoma, gastroblastoma, parietal cell carcinoma, oncocytic adenocarcinoma, Paneth cell carcinoma, gastric adenocarcinoma of the fundic gland type, undifferentiated carcinoma, and extremely well-differentiated adenocarcinoma. Although these diseases have different nomenclatures characterized by distinct histopathological features, these phenotypes often overlap, making it difficult to draw clear boundaries. Furthermore, the number of cases was limited, and the unique histopathological nature and potential pathogenic mechanisms were not well defined. This review highlights the importance of understanding these rare variants for accurate diagnosis, effective treatment planning, and improving patient outcomes. This review emphasizes the need for ongoing research and case studies to enhance our knowledge of these uncommon forms of gastric cancer, which will ultimately contribute to more effective treatments and better prognostic assessments. This review aimed to broaden the pathological narrative by acknowledging and addressing the intricacies of all cancer types, regardless of their rarity, to advance patient care and improve prognosis.

Switch/Sucrose Non-Fermentable Complex-Deficient Rhabdoid Carcinoma of Stomach: A Rare Case Report and Literature Review

Gastric undifferentiated/rhabdoid carcinoma is a rare highly invasive tumor of epithelial origin. Due to mutations in the switch/sucrose non-fermentable (SWI/SNF) complex, these tumor cells are usually dedifferentiated, presenting a characteristic rhabdoid profile. In this report, we present a gastric rhabdoid carcinoma in a 77-year-old man who presented with intermittent epigastric pain. Gastroscopy revealed a giant ulcer in the antrum, which proved to be a malignant tumor in the biopsy. Therefore, he was admitted to our hospital and underwent laparoscopic radical gastrectomy and D2 lymphadenectomy. The resected neoplasm contained a variety of rhabdoid cells that lacked well-differentiated elements. Immunohistochemical staining revealed that SMARCA4/BRG1 expression was absent in tumor cells. Finally, the patient was diagnosed with undifferentiated/rhabdoid carcinoma of the stomach. The patient was treated with tegafur-gimeracil-oteracil potassium capsules postoperatively. There were no signs of imaging changes observed at the 18-month follow-up. We reviewed similar cases in previous reports. These tumors are more likely to affect older male adults and usually lack typical symptoms. Histologically, most tumor cells are poorly cohesive and rhabdoid, and differentiated compositions of various degrees can occasionally be seen. Positive staining for vimentin was seen in all tumor cells. Epithelial markers are positive in the majority of tumors. SWI/SNF mutant tumors tend to be associated with a poor prognosis. In this review, more than half of the patients died within one year after surgery. The treatments for these diseases are still being explored.

Vimentin-positive gastric adenocarcinoma arising in a hyperplastic polyp

We report a case of vimentin-positive early gastric adenocarcinoma arising in a hyperplastic polyp (HP). A 72-year-old Japanese man was admitted for the detailed examination of a gastric polyp. He had a subtotal gastrectomy due to acute abdomen 12 years ago. Upper endoscopy revealed a pedunculated polyp measuring approximately 2 cm on the greater curvature of upper body of the remnant stomach. Magnifying endoscopy revealed that the microsurface pattern was irregular and partially absent accompanied with irregular microvessels at the upper end of the polyp. We speculated that the lesion was an adenocarcinoma arising in the HP. Endoscopic submucosal dissection (ESD) was performed. Histological examination of the ESD specimen revealed that the lesion consisted of well- to poorly differentiated adenocarcinoma at the protruding lesion and foveolar hyperplastic epithelia at the base of the polyp. Immunohistochemically, most of tumor cells that comprised poorly-differentiated adenocarcinoma were positive for both cytokeratin and vimentin. Although carcinomas have occasionally been found in HPs, the histological features of the present case are considered extremely unusual. To the best of our knowledge, this is the first case of vimentin-positive early gastric carcinoma arising in a HP.

Malignant rhabdoid tumour in the stomach

In this case report, a rare tumoral morphology in the gastrointestinal system is introduced. Malignant rhabdoid features are rarely observed in the gastrointestinal system but this discrimination is important due to the tumor's poor prognosis, aggressive behavior and early metastasis.

Mucin-secreting gastric adenocarcinoma with Rhabdoid areas

Rhabdoid tumor, first described in kidneys of infants and children, is an aggressive tumor that has been reported in several extrarenal locations. In this report, we describe the case of a 40-year-old patient with gastric adenocarcinoma composed of histologically well-differentiated glandular areas and focal rhabdoid zones. The rhabdoid component showed typical features such as abundant eosinophilic cytoplasm, eccentric nuclei, prominent nucleoli and intense focal positive immunohistochemical cytoplasmic reaction for vimentin. Recognition of the rhabdoid phenotype in gastrointestinal tract neoplasms is important because this feature is associated with poor prognosis and unresponsiveness to conventional therapy.

Neuroendocrine carcinomas of the pancreas with 'Rhabdoid' features

Neuroendocrine carcinomas of the pancreas are rare neoplasms whose morphologic features generally mirror those seen in neuroendocrine tumors in other organs. Rarely, however, they may display unusual morphologic appearances that can introduce difficulties for diagnosis. We report four cases of primary neuroendocrine carcinomas of the pancreas (islet cell tumors) that were characterized by prominent "rhabdoid" features of the tumor cells. The lesions occurred in two men and two women 37-79 years of age who presented with symptoms of biliary obstruction and epigastric pain; one patient had recurrent gastric ulcers and an elevated gastrin level. The tumors were located in the head and tail of the pancreas and measured 2.5-4.5 cm in greatest diameter. Histologic examination revealed sheets of monotonous tumor cells with uniform round nuclei showing dispersed chromatin and containing abundant densely eosinophilic cytoplasmic inclusions that displaced the nuclei toward the periphery. In all cases, the rhabdoid elements appeared to merge with areas showing a more conventional neuroendocrine morphology. Immunohistochemical studies in all cases showed strong cytoplasmic positivity of the rhabdoid tumor cells for chromogranin, synaptophysin, and cytokeratin. Recognition of this unusual morphologic appearance is of importance to avoid mistaking these lesions for other types of malignant neoplasm.