دانلود رایگان مقاله تومور برخورد آدنوکارسینوما-کارسینوئید راست روده در کولیت اولسراتیو

Abstract

A case of a collision carcinoma–carcinoid tumor of the rectum that arose in ulcerative colitis (UC). The patient was a 78-year-old man with a rectal tumor, who was diagnosed as having UC at 70 years of age. The tumor was diagnosed by endoscopy as a deep submucosal invasive rectal carcinoma. The patient underwent trans-anal local excision. Pathological examination of Hematoxylin–Eosin stained slides showed two different histological types: a conventional well differentiated tubular adenocarcinoma with submucosal invasion, and another that was composed of small cells with uniform nuclei and eosinophilic granular cytoplasm arranged in a trabecular pattern. Immnohistochemically, these cells were positive for chromogranin A and CD56. These cells exhibited a Ki-67 index that was less than 2% and mitosis in less than 1/10 HPF. These areas showed clear margins. Therefore, this tumor was considered to be a collision carcinoma–carcinoid tumor. Ultimately, the patient died 2 years after the local excision due to recurrence. Collision carcinoma–carcinoid tumors arising in ulcerative colitis are extremely rare. Collectively, it is considered that the behavior of the collision tumor is relatively aggressive. More careful surveillance of colorectal collision or composite carcinoma–carcinoid tumors is necessary, even when the carcinoma is early stage or the carcinoid is small.

3. Discussion

In the present case, adenocarcinoma and a typical carcinoid tumor were found concurrently in a rectal tumor. Usually, it is not easy to morphologically distinguish a collision tumor from a composite tumor. In composite tumors, two types of tissue exist within the same tumor, and are intermingled with each other in a similar proportion [11]. In collision tumors, the two elements are adjacent to one another without intermixture of individual cell types (“side by side” or “one upon another” pattern) [9,12–14]. In the present case, the tissue components apparently grew from side by side with a readily identifiable line of interface. Thus, this was compatible with a collision tumor. The association between carcinoid and inflammatory bowel disease (IBD), both in UC and Crohn's disease, has been reported as a consequence of hyperplastic changes in neuroendocrine cells [6]. Rectal NETs are usually located as solitary nodules in the submucosal layer. In UC patients, most tumors arise from inflamed areas [5,15]. Almost all cases of rectal NETs in IBD are found incidentally after surgery for IBD [6]. In the present case, the carcinoid component was also found incidentally. Cases of colorectal carcinoid and colorectal adenocarcinoma arising in UC have been reported as another lesion that present synchronously [6,16–18], and as a composite tumor [11,19,20], but not as a collision tumor.