This report discusses the case of a 20-year-old female patient who presented with acute abdominal pain, nausea, and vomiting. Initial laboratory analyses suggested an inflammatory process, but imaging studies failed to reveal pathologies. The patient underwent a diagnostic laparoscopy, which showed a thickened and multicystic appendix with signs of acute inflammation. Pathology indicated a positive cytology for malignancy, with a grade 1 mixed well-differentiated neuroendocrine tumor (NET) and high-grade mucinous neoplasm identified in the middle and distal thirds of the appendix. Finding both tumors in the same patient is extremely rare and has been reported in a few cases. The case emphasizes the importance of considering appendiceal tumors in the differential diagnosis of acute abdominal pain, even in young patients, and highlights the value of laparoscopy in their diagnosis. The early detection and appropriate management of appendiceal tumors are crucial for improving patient outcomes.