[A Case of Appendiceal Neuroendocrine Tumor Diagnosed after Appendectomy].

A 49‒year‒old woman presented to our hospital with right lower abdominal pain that had been presenting for about 6 days without any improvement. An abdominal CT examination demonstrated an enlarged appendix and stercolith of appendix with inflamed surrounding adipose tissue. Antibiotic treatment was administered, but an abdominal CT examination taken 3 days later showed worsening inflammation around the appendix. An appendectomy was laparoscopically performed. Upon resection, the enlarged appendix was found. In immunohistochemical staining, the resected tissue was positive for neuroendocrine markers, including chromogranin A, synaptophysin, Ki‒67, and a definitive diagnosis of neuroendocrine tumor(NET)G1 was obtained. The patient has been followed up without additional resection or adjuvant chemotherapy, and no recurrence has been observed. Appendix NETs are often diagnosed incidentally, as in this case. In treating appendicitis, it is essential to perform pathological examination of the resected specimen.