Acute appendicitis associated with an appendiceal carcinoid tumor

Abstract

A 28-year-old man presentedwith acute periumbilical pain for 1 day. The pain had started in the periumbilical region and then shifted to the right lower quadrant with intermittent abdominal cramps. He visited the hospital and was admitted with the suspicion of acute appendicitis. He was afebrile and hemodynamically stable. No rebound tenderness or abdominal guarding was noted during the physical examination. The appendix could not be visualized by ultrasonography. A computed tomographic scan showed an edematous and dilated appendix with fecolith and one nodular lesion over the proximal part of the appendix (Fig. 1A, arrow). The patient underwent appendectomy, and the gross picture of the appendix showed a white solid mass (1.2 cm in greatest diameter; Fig. 1B, arrow). The postoperative histological examination (Figs. 1C and 2AeD) revealed a Grade 1 neuroendocrine tumor (NET G1; carcinoid). Over the past 2 decades the term “carcinoid tumor” has commonly been used for well-differentiated neuroendocrine neoplasms that have a relatively benign prognosis. According to the newest World Health Organization nomenclature and classification of neuroendocrine neoplasms of the digestive system, a typical carcinoid is classified as a Grade 1 neuroendocrine tumor (NET G1). Appendiceal neuroendocrine tumors are rare and one of more unusual histopathological findings (about 0.37%) when examining appendectomy specimens. Nonetheless, they are the