Neuroendocrine tumor of the appendix associated with an appendiceal mucocele: an incidental discovery during breast tumor surveillance.

Neuroendocrine tumors of the appendix are rare but clinically significant tumors, often discovered incidentally during surgical procedures or radiological investigations for other abdominal conditions. When they occur in association with an appendiceal mucocele, another uncommon entity characterized by abnormal dilation of the appendix due to mucus accumulation, these concurrent findings can present diagnostic and therapeutic challenges. Herein, we report the case of a 54-years-old female, previously diagnosed and treated for early-stage breast cancer. During routine surveillance, an abdominal ultrasound revealed a suspicious mass in the region of the appendix. The patient underwent abdominal computed tomography followed by abdominal magnetic resonance imaging, which demonstrated a heterogeneous mass in the right lower quadrant. The patient underwent an appendectomy and resection of the tumor.