Case report: Metastasis of Merkel cell carcinoma in the small intestine

Merkel cell carcinoma is a rare primary neuroendocrine malignant neoplasm of the skin, which recurs in about 40 % of cases. The main factors are Merkel cell polyomavirus (MCPyV) and mutations caused by ultraviolet radiation [Paulson, 2018]. In this study, we report a case of Merkel cell carcinoma with metastasis to the small intestine. In a 52-year-old woman, a subcutaneous formation of a nodule up to 2.0 cm in diameter was detected during the examination. This neoplasm was removed and sent for histological analysis. Dot-like expression of CK pan, CK 20, chromogranin A, and Synaptophysin was observed in tumor cells, and Ki-67 in 40 % of tumor cells. There is no reaction in tumor cells to CD 45, CK 7, TTF 1, and S100. The morphological picture corresponded to Merkel cell carcinoma. A year later, the patient underwent surgery for intestinal obstruction. The pathohistological changes and immunophenotype of the small bowel tumor were consistent with Merkel cell carcinoma metastasis.

Helicobacter pylori attachment-blocking antibodies protect against duodenal ulcer disease

The majority of the world population carry the gastric pathogen Helicobacter pylori. Fortunately, most individuals experience only low-grade or no symptoms, but in many cases the chronic inflammatory infection develops into severe gastric disease, including duodenal ulcer disease and gastric cancer. Here we report on a protective mechanism where H. pylori attachment and accompanying chronic mucosal inflammation can be reduced by antibodies that are present in a vast majority of H. pylori carriers. These antibodies block binding of the H. pylori attachment protein BabA by mimicking BabA's binding to the ABO blood group glycans in the gastric mucosa. However, many individuals demonstrate low titers of BabA blocking antibodies, which is associated with an increased risk for duodenal ulceration, suggesting a role for these antibodies in preventing gastric disease.

Neuroendocrine Tumor of the Fallopian Tube and Serous Adenocarcinoma of the Ovary: Multicentric Primary Tumors

Neuroendocrine tumors (NETs) comprise a large group of tumors that are most often localized in the gastrointestinal tract and lungs. They are rarely found in the organs of the female reproductive tract; such NETs are primarily localized in the ovaries. We present a case of multicentric primary low-grade NET of the fallopian tube and high-grade ovarian serous adenocarcinoma. In both tumor regions, the histotypes of neoplasms were determined by morphological and immunohistochemical investigations. The NET of the fallopian tube was diffusely positive for chromogranin A and CD56, but wild type for p53 and negative for CK7, CK20, and ER; Ki-67 expression was observed in 3% of the neoplastic cells. The ovarian serous adenocarcinoma was positive for CK7 and ER, mutant for p53, but negative for chromogranin A, CK20, and CD56; Ki-67 expression was observed in 45% of the tumor cells. These results support the possibility that NET can occur in the female reproductive tract and coexist with other malignant tumors.