Finding of a Urachal Cyst in a Patient Presenting With an Acute Abdomen due to Appendicitis.

Urachal cysts are rare congenital anomalies in adults and are often identified incidentally during imaging studies or surgery because most remain asymptomatic. They represent the most frequent subtype of urachal anomaly. The simultaneous occurrence of acute appendicitis and a urachal cyst is exceptionally rare, with only a handful of cases reported in the literature. We describe the case of a 49-year-old man with a history of heart failure and substance use who presented with acute abdominal pain. Computed tomography (CT) demonstrated acute appendicitis and incidentally revealed a large cystic lesion adherent to the bladder dome, suggestive of a urachal cyst. Exploratory laparotomy confirmed suppurative appendicitis and a noncommunicating urachal cyst measuring 11 × 10 × 8 cm. Complete cyst excision and appendectomy were performed during the same procedure. Histopathological examination confirmed benign urachal tissue lined by transitional epithelium without dysplastic changes, together with transmural acute appendicitis. The postoperative course was uneventful, and the patient was discharged on the third postoperative day. This case emphasizes that urachal anomalies may be encountered as incidental findings during the evaluation of acute abdomen. Although infection is the most common clinical manifestation, urachal cysts may also be identified unexpectedly during surgery for unrelated conditions. Complete surgical excision provides definitive treatment while reducing the risk of recurrence and potential malignant transformation.