Acute appendicitis is a common surgical emergency that can be challenging to diagnose due to its varied clinical presentations. Standard imaging methods include ultrasonography, computed tomography (CT), and Magnetic resonance imaging (MRI), but fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT), typically used for oncology, can incidentally detect appendicitis through increased radiotracer uptake associated with inflammation. The paper discusses two cases where acute appendicitis was identified during PET/CT scans conducted for cancer evaluations. In cancer patients, diagnosing appendicitis is difficult due to overlapping symptoms from chemotherapy, metastasis, or radiation effects. Clinicians and radiologists must remain vigilant for incidental appendicitis findings in PET/CT scans, as early diagnosis can prevent complications despite its rarity in oncology imaging.