Abstract
Pulmonary carcinoid tumorlets are a cluster of neuroendocrine cells in the lung, which invade the basement membrane and are less than 5 mm in size. While similar to carcinoid tumors in all regards, they are differentiated from carcinoid tumors purely based on their size. They are generally considered benign, but lymph nodal involvement has been described in the past. It is unclear if lymph nodal involvement is due to metastasis to the lymph node or synchronous de novo proliferation of neuroendocrine cells in the lymph node as well. Here, we describe a patient with adenocarcinoma of the lung who was incidentally detected to have a pulmonary carcinoid tumorlet and a carcinoid tumorlet in the mediastinal lymph node.