it is widely accepted that patients with ulcerative colitis have an increased risk of developing colorectal cancer . if epithelial dysplasia or carcinoma is diagnosed on surveillance colonoscopy , experts recommend elective colectomy . the rates of malignant lymphoma and sarcoma have also been reported to be higher in patients with inflammatory diseases , although the etiology is not fully understood . a patient with a 14-year history of ulcerative colitis found to have sigmoid colon carcinoma with focal neuroendocrine differentiation a 32-year - old male patient with a 14-year history of ulcerative colitis ( uc ) , total colitis type , was followed at another hospital . the patient underwent steroid therapy for about two years , and stopped three years ago . only 5-asa was administered as maintenance therapy , and he was symptom - free for the last three years . on annual colonoscopy , a slightly elevated 2-cm lesion with small central ulcer was seen in the sigmoid colon ( fig . the surrounding colonic mucosa was pale and rough , suggesting a quiescent phase of uc activity . biopsies of the lesion showed well - differentiated tubular adenocarcinoma . computed tomography ( ct ) showed partial wall thickening of the sigmoid colon with no lymphadenopathy or distant metastases . he was diagnosed with sigmoid colon carcinoma associated with uc , and laparoscopic - assisted total colectomy with an ileal pouch - anal anastomosis was performed . the histopathology of the specimen revealed a tubular adenocarcinoma invading to the muscularis propria ( pmp ) with focal neuroendocrine differentiation ( fig . 2 b , 3 a ) which stained positive for both chromogranin a ( fig . the mucosa from the sigmoid colon to the rectum appeared to be atrophic , macroscopically . there were fibrotic changes with increased lymphoid follicles in the submucosal layer microscopically , suggesting a long history of chronic inflammation secondary to uc . the malignant tumor in the sigmoid colon was consistent with a tumor arising from chronically inflamed colonic mucosa secondary to uc . two of 15 regional lymph nodes were found to be positive ( adenocarcinoma , pn1 ) , and the lesion was diagnosed as stage iiia according to the general rules of japanese classification of colorectal carcinoma . the extent of colitis and duration of the disease are the most important risk factors for the development of colorectal carcinoma . however , patients with net associated with inflammatory bowel disease have rarely been reported , . a literature search including papers published from 1980 to 2015 showed only 13 patients with net associated with uc ( table 1 ) . patients in whom the carcinoid tumor was not directly associated with a dysplasia - associated lesion or mass or adenocarcinoma in uc ( colitic cancer ) were excluded , because carcinoid tumors can be diagnosed sporadically . ten of 13 lesions were found in the recto - sigmoid , and five patients had distant metastases at the time of diagnosis . three patients died from the disease within 15 months , although eight reports did not mention the outcome . these findings suggest a higher malignant potential of the disease compared to typical colitic carcinoma associated with uc . risk factors are the same as colitic carcinoma including a long duration of mucosal inflammation and pan - colitis type of uc . dysplasia - associated lesions or masses ( dalm ) are elevated areas known to have an increased risk for the development of adenocarcinoma in uc . dalms and inflammatory polyps are occasionally seen on surveillance colonoscopy in patients with uc , . a dalm does not appear like a typical adenomatous polyp , but often has a different appearance such as flat , granular , depressed and others . in contrast , neuroendocrine tumors of the colon and rectum usually appear as a submucosal tumor in the early stages , and as type 2 or type 3 lesions in advanced stages . in this patient , the tumor showed a slightly elevated lesion with small central ulcer , and the margin was unclear . based on the 2010 world health organization classification , net is stratified into two types , neuroendocrine carcinoma and mixed adeno - neuroendocrine carcinoma ( manec ) , according to the proportion of neuroendocrine cells and adenocarcinoma cells . manec is defined as a lesion with more than 30% neuroendocrine cells . in this patient , the proportion of cells with neuroendocrine features was less than 30% , meaning a diagnosis of net ( or colorectal carcinoma with focal neuroendocrine feature ) , not manec . as for net in the gastrointestinal tract , cisplatin / etoposide is a standard chemotherapy regimen . however , most nets in the colon and rectum were manec in our previous study . manec has a greater component of adenocarcinoma elements , and the efficacies of both irinotecan / cisplatin and 5-ffluorouracil based chemotherapy have been reported for some patients with manec . adjuvant chemotherapy for patients with manec should also be considered because some reports indicated its effectiveness , . in the present patient , all metastatic lymph nodes appeared to be adenocarcinoma , and capesitabine was given as adjuvant therapy for six months . it is not yet clear which chemotherapy regimen is most effective in patients with manec ( or colorectal cancer with neuroendocrine features ) , because few cases have been reported . although colorectal carcinomas are the most frequent tumors found in patients with ibd , other types of tumors have been associated with inflammatory bowel disease , such as lymphoma and sarcoma . one hypothesis is that chronic inflammation of the colonic mucosa may cause pancellular damage involving epithelial , goblet , paneth and neuroendocrine cells , resulting in pancellular dysplasia . it has been also hypothesized that the development of neuroendocrine tumors may be secondary to distant secretion of cytokines ( transforming growth factor alpha , proinflammatory cytokines , interferon gamma , tumor necrosis factor alpha , and interleukins ) . the combination of both inflammation related pancellular dysplasia and secretion of systemic mediators may partially explain the development of neuroendocrine tumors in ibd patients . serum chromogranin a has been reported to be elevated in patients with advanced disease and those who have elevated at diagnosis . following serum chromogranin a levels in patients with advanced neuroendocrine tumors a very rare case of sigmoid colon carcinoma with neuroendocrine features arising in a patient with uc was described . evaluation of more patients is needed to define an optimal treatment strategy for patients with this disease . we received approval from the ethics committee , and got informed consent of the patient .
highlightscolorectal carcinomas with neuroendocrine differentiation in uc are rare entity.most of clinical presentations are shared with adenocarcinomas associated with uc 
 . however , malignant potential may be higher.surgical treatment should be recommended , if tumors are resectable.best chemotherapy for this tumor is unknown , and further studies are required .