Neuroendocrine neoplasms of the jejunum: a heterogeneous group with distinctive proximal and distal subsets.

Neuroendocrine tumors (NETs) of the jejunum are rare and usually grouped with either duodenal or ileal NETs. We aimed at better evaluating their characteristics by studying 116 cases of small-bowel NETs for which a precise anatomical location was available. Thirty-four cases were duodenal. Eighty-two were located after the duodenojejunal ligament, including ten cases in the first 50 cm, four cases between 50 and 100 cm, and six cases between 100 and 250 cm. All tumors located after 50 cm from the duodenojejunal ligament were enterochromaffin neoplasms. In contrast, the ten tumors located before this point formed a heterogeneous group. They included two cases of gastrin-expressing tumors in the first 10 cm and one case of enterochromaffin tumor located at 45 cm. The seven remaining cases were large tumors, located between 10 and 50 cm, of intermediate or high histological grade (four out of seven G2 or G3), locally invasive and usually metastatic (five out of seven with liver metastases); their survival was comparable to that of duodenal NETs. Patients with tumors located in the duodenum or the first 50 cm of the jejunum had longer survivals than those with lower jejunal and ileal tumors (p = 0.024). In conclusion, our study underlines the heterogeneity of jejunal NETs and supports the distinction between "upper" and "lower" jejunal tumors, which, for prognostic purposes, might be grouped with, respectively, duodenal and ileal NETs. Our data suggest that the arbitrary limit between upper and lower jejunal tumors might be fixed at 50 cm from the duodenojejunal ligament.