P373 An Unusual Occurrence of Right-sided Colonic Neuroendocrine Carcinoma in Ulcerative Colitis – A case report

Background

It's estimated that inflammatory bowel disease (IBD) accounts for 1-2% of all colorectal cancer (CRC) cases. However, the mere presence of IBD increases the risk by 2 folds compared with the general population. It's been established that the most prevalent epithelial colonic malignancy linked to IBD is adenocarcinoma. Neuroendocrine neoplasms arising in the large intestines are extremely rare (rate <1%), even less common in association with IBD.⁽¹⁾

Herein, we report a 49 years-old male with a longstanding history of ulcerative pancolitis, who was found to have a metastatic right-sided colorectal neuroendocrine carcinoma (NEC).

Methods

Case Presentation
A 49-years-old male patient, with a 13-years history of ulcerative pancolitis underwent a colonoscopy. It revealed a large ulcerated mass extending from the ileocecal valve into the proximal ascending colon highly suspicious for malignancy. Biopsy showed a large cell poorly differentiated NEC in the ascending colon. Tumor cells were positive for Synaptophysin and cytokeratin AE1/3, and a high Ki67. Serum Chromogranin A (CgA) and urine 5-hydroxyindoleacetic acid were high. Imaging was evident for a short segment circumferential wall thickening at the ascending colon and hepatic metastasis. The patient was planned to receive chemotherapy, but died before treatment.

Results

Discussion

Risk of CRC increments linearly approximately 7 years following diagnosis of IBD. After 30 years of colitis, the incidence is estimated to be around 18%. NECs in particular are not frequently encountered in association with IBD, much less right-sided.⁽¹⁾ Colonic NECs are usually aggressive with a Ki67 typically greater than 20%, often present with metastasis with absence of a characteristic hormonal secretion picture.^{(2, 3)}

The incidence of NECs in association with Ulcerative Colitis (UC) is twice more frequent in males, with a mean age of 49.36, and development after a median of 15 years of UC first diagnosis. Majority of NECs were found in the left side of the colon, in the contrary to our patient. Prognosis was dismal in most cases, as most demonstrated a higher malignant potential compared to adenocarcinomas.⁽³⁾

Early diagnosis of gastrointestinal NECs poses a challenge since it lacks a specific clinical presentation. Serum CgA level correlates with the tumor burden and overall survival. Additionally, studies demonstrating the role of endoscopic surveillance in colonic NECs early detection is scarce.^(1,4)