Amyloid light-chain (AL) amyloidosis is associated with plasma cell disorder and monoclonal light chains. This type of amyloidosis is the prominent type involving the gastrointestinal tract. Monoclonal gammopathy of undetermined significance (MGUS) is the most common plasma cell disorder and a known precursor of more serious diseases. A 72-year-old male was treated for high blood pressure, diabetes, and gout at the clinic of a private physician. Due to a positive fecal occult blood test discovered during colon cancer screening, he underwent colonoscopy and was diagnosed with adenomatous polyps by biopsies. Two months later, he was referred to our hospital for endoscopic resection of the polyps. Although the polyps were successfully removed, a colonoscopy revealed two types of ulcerative lesions. Immunohistopathological evaluations obtained from these lesions and polyps confirmed amyloid deposition. Although esophagogastroduodenoscopy results were normal, a biopsy specimen from the patient’s stomach showed the same type of amyloid deposition. Immunoelectrophoresis showed M-proteins for anti-IgG-λ in the serum and λ type Bence-Jones protein in the urine. His blood, bone marrow, and urine test results led to a diagnosis of MGUS. A coronary angiography revealed multivessel stenosis, and the patient’s cardiac function improved after coronary artery stenting. Hereafter, a combination therapy with bortezomib, lenalidomide, and dexamethasone is planned. This is a case report of systemic AL amyloidosis caused by MGUS, which was incidentally detected by colonoscopy.

A 63-year-old woman presented to our hospital with elevated levels of serum IgG4, marked wall thickening of the gallbladder, hepatomegaly, and abdominal lymphadenopathy. She experienced a recurrent fever and leg edema. Her laboratory data demonstrated anemia, hypoalbuminemia, and elevated serum levels of interleukin-6 and C-reactive protein. The patient was eventually diagnosed with IgG4-related disease according to the comprehensive diagnostic criteria, although the patient exhibited common clinical manifestations of multicentric Castleman disease such as a fever, anemia, lymphadenopathy, and elevated levels of serum interleukin-6 and C-reactive protein. This case report highlights the difficulties in differentiating between these two diseases.

Although chemical-induced animal models of colorectal cancer (CRC) suggest a lot about the disease, more efforts are required to establish metastasis models. Azoxymethane (AOM) and dextran sodium sulfate (DSS)-treated (AOM/DSS) Crl:CD-1 mice were sacrificed after 10 or 20 weeks in our previous study, and most colon tumors exhibited intramucosal adenocarcinomas. Our observations were extended until 30 weeks to study a colitis-associated advanced CRC mouse model, and explore whether linker threonine-phosphorylated Smad2/3 (pSmad2/3L-Thr) immunostaining-positive cells were involved in the progressive course of colitis-associated CRC as cancer stem cells. AOM/DSS mice were sacrificed at 10, 20 and 30 weeks after AOM administration. Following the histopathological analysis, immunohistochemical staining was performed for the following markers: CD34, podoplanin, β-catenin, E-cadherin, Ki67, Bmi1 and pSmad2/3L-Thr. Compared with AOM/DSS mice at 10 and 20 weeks, submucosal tumor infiltration and tumor invasion into vessels were markedly increased at 30 weeks. In the parts of colon tumors from AOM/DSS mice, particularly in mice at 30 weeks, the positive signal of E-cadherin was clearly reduced in the cell membranes. The percentage of Ki67-positive tumor cells in mucosal areas of AOM/DSS mice was higher than that in the sites of submucosal infiltration. In mucosal areas of colon tumors, pSmad2/3L-Thr-positive cells were scattered among tumor cells. At sites of submucosal infiltration and vessel invasion of these tumors, pSmad2/3L-Thr-positive cells were also observed among tumor cells. In colon tumors from AOM/DSS mice at 30 weeks, the percentage of pSmad2/3L-Thr-positive cells among the nuclear β-catenin-positive tumor cells was higher than that among the cytoplasmic β-catenin-positive tumor cells. For both non-neoplastic and neoplastic epithelial cells, pSmad2/3L-Thr-positive cells exhibited immunohistochemical co-localization with Bmi1. The present study developed an advanced CRC mouse model that exhibited tumor infiltration into the submucosa and invasion into vessels. The present study re-confirmed the theory that pSmad2/3L-Thr-positive cells may be cancer stem cells.

The human gastrointestinal tract, which constitutes the digestive system, contains a large number of virus particles that maintain organizational homeostasis and health. Conversely, viral pathogens have also attracted attention for their involvement in the pathogenesis of certain cancers, including gastrointestinal cancers. To aid prevention and treatment of these cancers, the relevance of gastrointestinal viral factors as potential risk factors needs to be carefully investigated. This review summarizes and discusses the available literature on the relationship between the development of esophageal, gastric, and colorectal cancers and their corresponding viruses. This review reveals that research on the association between colorectal cancer and viruses, in particular, is still in its infancy compared to the association between HPV and esophageal cancer and between EBV and gastric cancer.

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