Pancreatic neuroendocrine tumours.

INTRODUCTION: Pancreatic neuroendocrine tumours (PNT) are infrequent epithelial neoplasms associated with a better outcome than pancreatic adenocarcinoma. MATERIALS AND METHODS: We analysed our 22 years of experience in managing PNT. Forty-nine patients (27 women and 22 men) with a mean age of 49 years were studied. There were 28 insulinomas, eight glucagonomas, three gastrinomas, one VIPoma and one carcinoid. Eight patients presented with nonfunctional tumours. Enucleation was performed in 20 patients, distal pancreatectomy in 16, middle pancreatic resection in four, cephalic pancreatoduodenectomy in two and total pancreatoduodenectomy in one. In six patients, the tumour was not resected. RESULTS: Postoperative complication rate was 22%: six pancreatic fistulas, three intra-abdominal collections, one remnant pancreatitis and one pancreatic pseudocyst. There was no mortality. 39 cases showed benign histologic features and ten malignant ones. Symptomatic palliation was achieved in 94% of the cases. Five patients presented recurrences: three liver metastases and two pancreatic recurrences. Actuarial mean survival was 163 months and was longer in insulinomas, in those tumours completely resected and in tumours with benign histological features. CONCLUSION: Conservative surgery of the pancreas is preferred, but aggressive surgery is indicated when the primary tumour can be controlled. Despite of minimising pancreatic resection, there is a high complication rate, mainly pancreatic fistulas, though they can often be conservatively managed. Insulinomas are the PNT with better outcome; those completely resected also associate a better prognosis.

Peritoneal carcinomatosis secondary to carcinoid tumour.

Carcinoid tumours are neuroendocrine neoplasms that can appear in every location of the digestive tract. They are low aggressive tumours, although they often produce local invasion and hepatic metastases, whose resection allows long-term survival. We report a case of a 64-year-old man with ileal carcinoid tumour, that underwent ileal resection and metastasectomy of one lesion in liver segment II. Surgical findings indicated peritoneal carcinomatosis. Carcinoid dissemination as peritoneal carcinomatosis has been rarely described in the literature. Cytoreductive surgery, always when complete resection is aimed, achieves asymptomatic long-term survivals.

Pseudomyxoma peritonei secondary to epithelial appendicular neoplasms. Experience in a non-specialised centre.

INTRODUCTION: Pseudomyxoma peritonei is an infrequent entity, defined by collections of gelatinous material in the abdomen and pelvis and mucinous implants on peritoneum, secondary to the rupture of a mucinous lesion, usually of ovarian or appendiceal origin. MATERIALS AND METHODS: We present our experience of 11 cases (6 males and 5 females) diagnosed with pseudomyxoma peritonei secondary to epithelial appendicular neoplasms over 27 years. The mean age of the patients was 68 years. Clinical manifestations were abdominal distension (55%), right lower quadrant pain (45%) suggesting acute appendicitis and constitutional syndrome (36%). An abdominal mass was detected at physical examination in 4 patients. CT scan revealed a tumour in right iliac fossa in 4 patients, peritoneal enlargement in 1 and a liquid collection in 1. Preoperative diagnosis was acute abdomen in 5 patients, peritoneal carcinomatosis in 3 and undetermined abdominal mass in 3. RESULTS: Surgical findings suggested pseudomyxoma peritonei in 8 patients and peritoneal carcinomatosis in 3. Appendicectomy was performed in 9 patients, and in 3 of them bilateral anexectomy was also performed. One patient underwent ileocaecal resection and another a right hemicolectomy. In all the cases, mucinous material was eliminated as much as possible. Pathology revealed mucinous cystoadenoma in 6 cases, mucinous cystoadenocarcinoma in 3 and epithelial hyperplasia in 2 patients. Median survival was 54 months, with a 5- year survival rate of 40%. The last case we treated was sent to a reference centre for the treatment of pseudomyxoma peritonei. CONCLUSIONS: There is no consensus on the best treatment for pseudomyxoma peritonei. We recommend avoiding incomplete surgical resections in non-reference centres and submitting patients to a reference centre to undergo adequate treatment.

Mesorhizobium chacoense sp. nov., a novel species that nodulates Prosopis alba in the Chaco Arido region (Argentina).

Low-molecular-weight RNA analysis was performed for the identification and classification of 20 Argentinian strains isolated from the root nodules of Prosopis alba. SDS-PAGE of total cellular proteins, determination of the DNA base composition, DNA-DNA reassociation experiments and physiological and biochemical tests were also carried out for these strains and the whole 16S rRNA gene was sequenced from one of the strains, strain LMG 19008T. Results of the genotypic and phenotypic characterization showed that the strains isolated in this study belong to a group that clustered in the genus Mesorhizobium. The results of DNA-DNA hybridizations showed that this group is a novel species of this genus. The name Mesorhizobium chacoense sp. nov. is proposed for this species. The type strain is LMG 19008T (= CECT 5336T).