Abstract
Endocrine cell carcinomas are rare tumors in the gastrointestinal tract. Because of the high potential for metastasis in an early stage, the prognosis for endocrine cell carcinoma is poor. Adenoendocrine cell carcinomas are endocrine cell tumors in which an adenocarcinoma component is observed histologically. Here we report a case of adenoendocrine cell carcinoma of the rectum in a 68-year-old man. The tumor was identified originally by rectal examination and further bioptic examination was performed using colorectal endoscopy. Histopathological examination of the biopsy specimen resulted in a diagnosis of adenocarcinoma, and the patient underwent colectomy. Macroscopic findings showed a 3×5cm ulcerated carcinoma with heaped-up margins. In cross section, the tumor was gray-white in color and solid. Histopathologically, the tumor was characterized as invasive adenocarcinoma with a solid, ribbon-like, acinar growth pattern and with foci of goblet cell components. Immunohistochemical analysis revealed that keratin, AE1/AE2, Epithelial membrane antigen (EMA), Carcinoembryonic antigen (CEA), somatostatin and α-fetoprotein proteins (AFP) were expressed on the tumor cells, whereas Neuron-specific enolase (NSE), chromogranin A, gastrin, calcitonin and CD56 proteins were absent. Ki-67 protein was expressed weakly and sparsely in the nuclei of tumor cells. The sum of these findings resulted in our diagnosis of adenoendocrine cell carcinoma of the rectum.
