We present an 11-year-old pediatric patient with acute-on-chronic abdominal pain found to have a large intra-abdominal abscess with a concomitant dermoid cyst. Acute-on-chronic abdominal pain has one of the broadest and, in our case, ever-changing differential diagnoses. Exploratory laparoscopy revealed a severe pelvic inflammatory process with a large abscess and extensive omental and bowel adhesions, a left ovarian cyst, a shortened appendix with thickened tip, and purulent fluid in the cul-de-sac. These findings suggested a ruptured appendix leading to a large abscess with adjacent ovarian dermoid cyst, and an appendectomy was performed. Our patient responded well to continued intravenous antibiotics, and her drain was removed on the day of discharge. She was sent home with an additional 2 weeks of oral cefdinir and metronidazole. Follow-up ultrasound showed dramatic cyst resolution, and no further intervention was needed. [Pediatr Ann. 2023;52(1):e36-e38.].