Ileal “carcinoid” tumors—small size belies deadly intent: high rate of nodal metastasis in tumors ≤1 cm in size

Neuroendocrine tumors (NETs) account for 2% of tumors of the gastrointestinal tract, most occurring in the small intestine. A size of 2 cm is generally regarded as a cut-off point for risk of lymph node metastasis in intestinal neuroendocrine tumors in the absence of other high-risk features; however, metastatic disease has been reported in 12% of tumors of the jejunum and ileum measuring 1 cm or less. Archives from 2 institutions were searched for ileal NETs measuring 1 cm or less, and selected data were recorded. Twenty-one ileal NETs were identified measuring ≤ 1 cm. Six (29%) were multifocal and 7 (33%) had distant metastasis at diagnosis. Regional lymph nodes were examined in 14 cases (67%), and 10 of these cases (71%) showed lymph node metastasis. Mean primary tumor size in cases with nodal metastasis was 7.3 mm. In this series of ileal NETs ≤ 1 cm in size, the rate of lymph node metastasis was 48% overall and 71% for cases with regional lymph node resections. In addition, 33% showed distant metastasis at the time of diagnosis. Tumors as small as 3 mm and those confined to the submucosa can give rise to nodal metastasis, emphasizing the need for consideration of local resection with regional lymphadenectomy, even for subcentimeter ileal NETs.