A case of appendiceal neuroendocrine tumor with metastatic spread in a young patient.

Appendiceal neuroendocrine tumors are a rare subset of well-differentiated neuroendocrine tumors, comprising <1% of all malignancies. Appendiceal cancer is particularly rare, affecting approximately one to two individuals per one million annually in the United States. Appendiceal neuroendocrine tumors have an estimated incidence of 7/100,000 person-years in the United States. In this report, we present the case of a 19-year-old female who arrived to the emergency department with recurrent right lower quadrant pain, unresponsive to initial management for suspected acute appendicitis, and urinary tract infection. Advanced imaging revealed an appendiceal mucocele. The patient underwent appendectomy, and histopathology confirmed a well-differentiated appendiceal neuroendocrine tumor (grade 2) with lymphovascular invasion. A subsequent right hemicolectomy identified metastatic disease in 6 out of 27 lymph nodes. Unfortunately, the patient was lost to follow-up shortly after surgery. This case underscores the diagnostic complexities of appendiceal neuroendocrine tumors, which are often incidental findings during appendectomy and may present with nonspecific or atypical symptoms. It highlights the critical role of tumor size, grade, and histopathological evaluation in guiding management decisions, as well as the importance of a multidisciplinary approach to treatment. Moreover, it emphasizes the necessity of vigilant follow-up, particularly in young patients, to address the long-term implications of this rare malignancy and improve outcomes.