Neuroendocrine tumor of the rectum: A case report

Abstract

Neuroendocrine tumors are a frequent and clinically enigmatic group of tumors originating from the cells of diffuse neuroendocrine system. The incidence of neuroendocrine tumors of the rectum is 0.86 per 100,000 people. In our paper, the patient was 58 years old, sent to a gastroenterologist because of intermittent abdominal bloating and positive findings on a fecal occult test. Upper endoscopy diagnosed an ulcer in the duodenal bulb, which explained the positivity of the fecal occult test. Using colonoscopy at 10th centimeter in the rectum a sessile polypoid resizing of 15 millimeters was found, and the histopathologic findings showed that it was an interstitial colitis, without the elements of malignant cells. Computed tomography of the pelvis showed a lesion in the rectal region that had infiltrated the wall of the rectum without propagation to the surrounding structures and with no enlarged lymph nodes. Histopathological material was sent to immunohistochemistry, which showed that it were welldifferentiated neuroendocrine tumors, with the invasion of the lamina muscularis propria and positive staining for chromogranin A and neuron-specific enolase, and the nuclear antigen Ki-67 was 17%. The values of chromogranin A levels in serum were three times higher than normal. 15 months after the tumor was removed surgically, computerized tomography scan showed multiple lesions in the liver. Octreoscan (somatostatin receptor scintigraphy) confirmed multiple lesions in the liver with the expression of somatostatin receptors. A rare case of tumor was shown, diagnosed in a nonspecific way, that at the time of diagnosis, despite its size and infiltration into the muscle tissue did not have distant metastases.