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Surgical Robot-Assisted Transanal Specimen Extraction Radical Sigmoidectomy Without an Auxiliary Abdominal Incision
Published on: June 13, 2025
Composite neuroendocrine tumor and adenocarcinoma of the rectum
Hiromi Kanno-Okada1, Tomoko Mitsuhashi2, Katsuhiro Mabe3
1Department of Surgical Pathology, Hokkaido University Hospital, North 14, West 5, Kita-ku, Sapporo, Hokkaido, 060-8648, Japan. kanno-kanno@med.hokudai.ac.jp.
Background:
Although adenocarcinomas showing neuroendocrine differentiation or those mixed with high-grade neuroendocrine carcinoma (NEC) are sometimes encountered, composite tumors comprising neuroendocrine tumor (NET) Grade 1 and adenocarcinoma are exceedingly rare.
Case Presentation:
A 64-year-old male presented after testing positive for fecal occult blood at a medical check-up. A biopsy demonstrated the presence of a NET and endoscopic submucosal dissection was undertaken. Histologic examination revealed that a well differentiated tubular adenocarcinoma was present in addition to the NET. Furthermore, histological transition between the two tumors was evident. Accordingly, this case was considered to be a composite tumor comprising NET and adenocarcinoma.
Conclusion:
Composite tumors consisting of NET Grade 1 and adenocarcinoma are exceedingly rare, and only a few examples have been reported hitherto.
