Microscopic Carcinoid: An Unusual Presentation of Gastric Carcnioid

Abstract

51 year old Caucasian male with history of hyperlipidemia presented with complain of melena. Patient had noticed one episode of bright red blood per rectum. On questioning patient also complained of feeling tired lately with generalized body aches. He also had some numbness and tingling in both lower extremities which had been gradually worsening. Neurological exam showed decreased sensation, vibration and position sensation in both lower extremities. Digital rectal exam was positive for frank blood in rectal vault. Initial laboratory work up showed hemoglobin of 8.5 with MCV of 110. Patient underwent upper endoscopy which showed non-bleeding gastric ulcer. Also there were few scattered small focal areas of erythematous lesions in gastric cardia and proximal body with significant loss of the gastric folds. Biopsy of the lesions showed increase in fibrous tissue with moderate active inflammation of lamina propria and Chronic atrophic gastritis while rapid urease test was negative. Interestingly, carcinoid changes with chronic intestinal metaplasia were found on biopsy suspicious for carcinoid tumor. Given the finding on biopsy, fasting serum Gastrin Chromogranin A levels, Parietal cell antibodies, Intrinsic Factor antibodies, 24 hour urine for 5-HIAA, Computerized tomography (CT) scan of the abdomen and pelvis, and Octreotide scan were ordered to look for primary location of carcinoid tumor. Fasting serum Gastrin Chromogranin A levels, Parietal cell antibodies, Intrinsic Factor antibodies were found to be elevated the diagnosis of Carcinoid Tumor but there were no mass lesions but only scattered cells in the stomach. Patient subsequently underwent frequent endoscopies with biopsies which reconfirmed well differentiated carcinoid tumor cells scattered in the stomach but no mass lesion. Meanwhile patient underwent extensive work up for peripheral neuropathy and was found to have vitamin B12 deficiencies in setting of atrophic gastritis leading towards diagnosis of pernicious anemia which was likely cause of the underlying carcinoid changes. Patient is currently treated with vitamin B12 with marked improvement in his symptoms and is undergoing Surveillance endoscopies of carcinoid changes. Discussion: Carcinoid tumors Originate from Enterochromaffin-like (ECL) cells, found in gastric wall. There are three types of gastric carcinoid tumors. Type 1 are smaller and less than 1 cm, multiple, polypoid lesions with central ulceration associated with chronic atrophic gastritis and pernicious anemia. Type 2 occurs in association with gastrinomas (Zollinger-Ellison syndrome), often in setting of MEN type 1 and are mostly indolent in nature. While type 3 are Sporadic as they occur in the absence of atrophic gastritis or the Zollinger-Ellison /MEN1 syndromes and are very aggressive in nature. They are characterized by normal gastrin level. Diagnosis for carcinoid tumors include biochemical testing including urinary excretion of 5-HIAA, Chromogranin level, Blood serotonin concentration, Gastrin level and Anti parietal cell antibodies. Tumor localization is done by CT, Magnetic resonance Imaging, Octreotide scan. Type 1 and 2 are treated with endoscopic resections and survelliant endoscopies. Treatment for type 3 gastric carcinoid tumors is partial or total gatstrectomy considering the aggressive nature. Conclusions: Carcinoid tumors usually appear as discrete masses but microscopic carcinoid tumor in stomach is a very rare.