Although rare, acute appendicitis presenting as a remote abscess with cellulitis in the gluteal region, retroperitoneal region, groin, or thigh does occur and may present a diagnostic challenge. We report a case of a 78-year-old woman presenting with an extensive gas-forming abscess in the right gluteal region secondary to perforated appendicitis without significant gastrointestinal symptoms. Computed tomography (CT) demonstrated a retroperitoneal abscess extending along the sacropelvic surface of the ilium to the subcutaneous tissue. Subsequently, laparotomy revealed retrocecal appendicitis perforated at the base of the cecum, and contained in the retroperitoneum without any signs of peritonitis. This case not only represents an unusual manifestation of acute appendicitis, but also alerts us to the importance of anatomical considerations when interpreting disease extent with imaging. In the differential diagnosis of gluteal or upper thigh abscesses, the rare possibility of perforated acute appendicitis should be considered.