BACKGROUND: The Toll-like receptor (TLR) 4 signalling pathway has been shown to have oncogenic effects in vitro and in vivo. To demonstrate the role of TLR4 signalling in colon tumourigenesis, we examined the expression of TLR4 and myeloid differentiation factor 88 (MyD88) in colorectal cancer (CRC). METHODS: The expression of TLR4 and MyD88 in 108 CRC samples, 15 adenomas, and 15 normal mucosae was evaluated by immunohistochemistry, and the correlations between their immunoscores and clinicopathological variables, including disease-free survival (DFS) and overall survival (OS), were analysed. RESULTS: Compared with normal mucosae and adenomas, 20% cancers displayed high expression of TLR4, and 23% cancers showed high expression of MyD88. The high expression of TLR4 and MyD88 was significantly correlated with liver metastasis (P ¼ 0.0001, P ¼ 0.0054). In univariate analysis, the high expression of TLR4 was significantly associated with shorter OS (hazard ratio (HR): 2.17; 95% confidence interval (95% CI): 1.15 -4.07; P ¼ 0.015). The high expression of MyD88 expression was significantly associated with poor DFS and OS (HR: 2.33; 95% CI: 1.31 -4.13; P ¼ 0.0038 and HR: 3.03; 95% CI: 1.67 -5.48; P ¼ 0.0002). The high combined expression of TLR4 and MyD88 was also significantly associated with poor DFS and OS (HR: 2.25; 95% CI: 1.27 -3.99; P ¼ 0.0053 and HR: 2.97; 95% CI: 1.64 -5.38; P ¼ 0.0003). Multivariate analysis showed that high expressions of TLR4 (OS: adjusted HR: 1.88; 95% CI: 0.99 -3.55; P ¼ 0.0298) and MyD88 (DFS: adjusted HR: 1.93; 95% CI: 1.01 -3.67; P ¼ 0.0441; OS: adjusted HR: 2.25; 95% CI: 1.17 -4.33; P ¼ 0.0112) were independent prognostic factors of OS. Furthermore, high co-expression of TLR4/MyD88 was strongly associated with both poor DFS and OS. CONCLUSION: Our findings suggest that high expression of TLR4 and MyD88 is associated with liver metastasis and is an independent predictor of poor prognosis in patients with CRC.

Little attention has been paid to colorectal xanthoma. To clarify the clinical and pathological features of colorectal xanthoma, we report 28 colorectal xanthomas biopsied from 25 patients. All were composed of typical xanthoma cells and showed polypoid configuration. Median age of the patients was 64 years and there were 15 men and 10 women. Diabetes mellitus, constipation, and hyperlipidemia were found in two, one, and seven patients, respectively. Seventeen (60.7%) of the 28 polyps were located in the sigmoid colon and the remaining 11 in the rectum. Twenty-three polyps (82.1%) were sessile. Twelve (60.0%) of twenty polyps that were recorded were reddish in color. Only two polyps revealed a yellowish tone. Microscopically, foamy cells were present in the lamina propria, but the submucosa did not contain foamy cells. Immunohistochemically, the foamy cells invariably expressed extensive positivity for CD68. The colonic glands showed a deformity in the case with moderate to intense density of the foamy cells. The surface epithelium showed a hyperplastic change in 22 (78.6%) xanthomas. The colonic glands in four xanthomas were also associated with hyperplastic changes. The basement membrane of the surface epithelium was often thickened. Cell debris and proliferation of the capillaries were observed just below the surface epithelium in 19 (67.9%) and 22 (78.6%) xanthomas, respectively. Previous mucosal minute injury was suggested as the pathogenesis of colorectal xanthomas. Colorectal xanthomas were not identical to gastric and esophageal xanthoma, endoscopically or microscopically. We prefer the term "xanthomatous polyp" rather than xanthoma in the colorectal region. They may be regarded as a novel type of colorectal non-neoplastic polyp.

The molecular pathogenesis of gastroenteropancreatic (GEP) neuroendocrine tumours (NETs) remains to be elucidated. Highmobility group A (HMGA) proteins play important roles in the regulation of transcription, differentiation, and neoplastic transformation. In this study, the expression of HMGA1 and HMGA2 was studied in 55 GEP NETs. Overexpression of HMGA1 and 2 was frequently detected in GEP NETs compared with normal tissues. Nuclear immunostaining of HMGA1 and 2 was observed in GEP NETs (38 of 55, 69%; 40 of 55, 73%, respectively). High-mobility group A2 expression increased from well-differentiated NET (WNET) to well-differentiated neuroendocrine carcinoma (WNEC) and poorly differentiated NEC (PNEC) (Po0.005) and showed the highest level in stage IV tumours (Po0.01). In WNECs, the expression of HMGA1 and 2 was significantly higher in metastatic tumours than those without metastasis (Po0.05). Gastroenteropancreatic NETs in foregut showed the highest level of HMGA1 and 2 expressions. MIB-1 labelling index (MIB-1 LI) correlated with HMGA1 and 2 overexpression (R ¼ 0.28, Po0.05; R ¼ 0.434, Po0.001; respectively) and progressively increased from WNETs to WNECs and PNECs (Po0.001). Let-7 expression was addressed in 6 normal organs, 30 tumour samples, and 24 tumour margin non-tumour tissues. Compared with normal tissues, let-7 downregulation was frequent in NETs (19 of 30, 63%). Higher expression of HMGA1 and 2 was frequently observed in tumours with let-7 significant reduction (53, 42%, respectively). The reverse correlation could be detected between HMGA1 and let-7 (Po0.05). Our findings suggested that HMGA1 and 2 overexpression and let-7 downregulation might relate to pathogenesis of GEP NETs.

Gastric inverted hyperplastic polyp (IHP) is a rare type of gastric polyp, and is characterized by downward growth of the hyperplastic mucosal components into the submucosa. To the best ofour knowledge, 16 gastric IHP cases have been described in the English literature, but the pathogenesis has not been established. We report the clinical and pathological findings of four gastric IHP cases. The lesions were mainly composed of hyperplastic foveolar-type glands with focal cystic dilatation. Pyloric type glands, endocrine cells, acinic cell metaplasia, and smooth muscle bundles were also seen as components of the polyp. Two cases (cases 1 and 4) coexisted with multifocal gastritis cystica profunda (GCP) and gastric adenocarcinoma. Case 4 furthermore exhibited an intermediate form between IHP and GCP. We suggest that IHP may be GCP associated with exaggeratedly hyperplastic and metaplastic changes. In case 4, the coexisting gastric carcinoma was mainly located in the submucosa, whilst the mucosal component was minimal. Five out of twenty reported gastric IHP cases, including our cases, coexisted with gastric adenocarcinoma. These facts would lead us to further investigate the relation between gastric IHP and carcinoma.