An unusual case of rectal carcinoid removed by transanal endoscopic microsurgery

The name ''carcinoid'' was invented by Oberndorfer in 1907, when the nature of those histological entities was little understood. Usually, they were found in various locations in the gastrointestinal (GI) apparatus (67%), most of them in the small intestine (25%), appendix (12%), and rectum (14%).The techniques used for their removal are various. The authors present here a case of rectal carcinoid removed using the transanal endoscopic microsurgery technique, and referred to the diagnosis and treatment of this uncommon tumor. A 37-year-old male was admitted to the Santa Maria Hospital of Terni (Italy) with a chief complaint of intermittent pain in the lower right quadrant, that began three years ago. Complete blood count (CBC) and laboratory data as tumor markers and urinary 5-hydroxyindoleacetic acid (5-HIAA) showed no abnormalities, while urinary vanilmandelic acid level was elevate (18 mg/24 h). The patient was submitted to a colonoscopy with magnifying endoscopy and biopsy. The histological finding demonstrated a nodule characterized by cellular proliferation, with few microscopical abnormalities, arranged in small cords with a glandular pattern, separated by dense connective tissue. Histochemically the tumor cells were cytocheratins +/-, chromogranin positive, synaptophysine positive, CD56 positive and Growth Index MIB1-Ki67 which was almost zero. The patient also underwent an endoscopic ultrasonography and an Octreoscan. He was operated using a transanal endoscopic microsurgery technique. The use of Transanal Endoscopic Microsurgery (TEM) as a safe and feasible technique for exciding rectal tumors can be easily understood, for the excellent view and precise dissection. The use of new surgical devices as Harmonic Scalpel has improved the precision of this kind of approach, increasing the appropriateness of this approach compared to other kind of resection. A full diagnostic course and an immunohistochemistry are mandatory for precise diagnosis of rectal carcinoid. Careful attention must be paid to these tumors because of their unexpected behaviour.