Endoscopic resection of rectal carcinoid tumors using aspiration lumpectomy.

BACKGROUND AND STUDY AIMS: Although carcinoid tumors have malignant potential, complete resection can be curative if the lesion is located within the submucosal layer. In this study, we evaluated the effectiveness of endoscopic aspiration lumpectomy for the treatment of small rectal carcinoid tumors. PATIENTS AND METHODS: Eight patients with rectal carcinoid tumors less than 10 mm in diameter and located within the submucosa were treated by aspiration lumpectomy. It was confirmed that none of the patients had any metastatic lesions before treatment. The procedure was carried out using an endoscope with a cylinder attached to the tip and a Teflon tube along its outer axis. The lesion was aspirated into the cylinder, grasped by a snare passed through the tube, and then resected. RESULTS: All lesions were excised completely, without any complications. The resected specimens were circular, with the lesions located in the center of the surrounding mucosa. The diameter of the specimens (mean +/- SD) was 18.3 +/- 6.2 mm. All tumors were histologically typical, and the lateral and bottom margins of the specimens were free of tumor cells. No recurrences or distant metastases were found in any of the patients during the mean observation period of 13.3 months. CONCLUSIONS: We conclude that aspiration lumpectomy is a useful and safe technique for the treatment of small rectal carcinoid tumors contained within the submucosa.

Serotonin activates electrolyte transport via 5-HT2A receptor in rat colonic crypt cells.

The aim of this study was to demonstrate that 5-HT activates electrolyte transport directly via 5-HT2A receptor in rat colonic crypt cells. Patch-clamp whole cell recording was performed in isolated crypts to measure the 5-HT-induced changes in electrogenic K+ and Cl- currents. Superfusing 5-HT (10 microM) in the bath solution increased both K+ and Cl- currents, which were antagonized by the presence of ketanserin (1 microM), a selective 5-HT2A antagonist, in the bath solution. Mesulergine (1 microM) a 5-HT2A and 5-HT2C antagonist, had no inhibitory effect. Strong chelation of the intracellular Ca2+ by 5 mM BAPTA inhibited 5-HT-induced currents. 5-HT also failed to activate K+ and C1- currents in the presence of GDPbetaS (0.5 mM) in the pipette solution. Intracellular administration of GTPgammaS (0.1 mM) mimicked the stimulatory effect of 5-HT, that was inhibited by 5 mM BAPTA. H-7 (0.05 mM), an inhibitor of protein kinase C, A, and G, did not affect the currents. These data indicate that a G protein-coupled pathway is involved in the activation of electrolyte secretion via 5-HT2A receptor.

Endosonographic characterization of duodenal elevated lesions.

BACKGROUND: Endoscopic diagnosis of duodenal elevated lesions is problematic for two reasons. Endoscopic biopsy often fails to confirm a histologic diagnosis of submucosal lesions. Moreover, a biopsy specimen is often insufficient to verify a differential diagnosis of mucosal lesions. In this study, we evaluated the usefulness of endosonography in the resolution of these problems. METHODS: The endoscopic and endosonographic features of 15 duodenal elevated lesions that had been confirmed histologically in our hospital were reviewed retrospectively. RESULTS: Of the 15 cases, 8 were submucosal lesions (lipoma, Brunner's gland hyperplasia, lymphangioma, carcinoid tumors, leiomyoma, and malignant lymphoma); the rest were mucosal lesions. A correct histologic diagnosis based on endoscopic biopsies was obtained in only 6 cases (three submucosal lesions and three mucosal lesions). On the other hand, ultrasonography was useful in the characterization of all submucosal lesions based on their echo level, layer of origin, and tissue homogeneity. As for mucosal lesions, the depth of infiltration was correctly estimated with endosonography. Either endoscopic resection or surgery was selected on the basis of endosonographic information. CONCLUSIONS: We conclude that endosonography is useful in the differential diagnosis of submucosal lesions and in determining suitable treatment methods for duodenal mucosal and submucosal lesions.