Appendiceal mucinous neoplasms are neoplastic appendicular lesions resulting from the abnormal accumulation of mucin in the appendix. These neoplasms can be asymptomatic or present with vague, nonspecific symptoms. Although generally considered benign, they carry the risk of severe complications such as pseudomyxoma peritonei. We present a 17-year-old boy with fever and suprapubic pain radiating to the right lower quadrant, with no definitive clinical, imaging, or intraoperative macroscopic diagnosis, who was found to have an appendiceal mucinous neoplasm. He underwent complete resection of the appendix with negative margins, without the need for further treatment. As a rare entity in pediatric patients, these neoplasms pose both diagnostic and therapeutic challenges with ongoing debate regarding the best surgical approach, appropriate adjuvant therapy, duration of follow-up, and imaging techniques for their management. This case highlights an unusual way of diagnosing an uncommon neoplasm.