A case of rectal MiNEN demonstrating vascular stalk-like imaging and gross demarcation of tumor components.

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) of the rectum are extremely rare and pose significant diagnostic challenges. We report a 69-year-old man with rectal MiNEN successfully treated with a robot-assisted Hartmann's procedure. Preoperative contrast-enhanced CT revealed a vascular stalk-like structure within the tumor. Gross pathology showed a clear demarcation between adenocarcinoma and small-cell neuroendocrine carcinoma. Robot-assisted surgery facilitated precise dissection in the narrow pelvic cavity and safe distal transection through a transanal approach. This case highlights unique radiological and pathological findings that may aid in the diagnosis and management of rectal MiNEN.