Primary osteomyelitis of the acetabulum resulting in septic arthritis of the hip and obturator internus abscess diagnosed as acute appendicitis.

The misdiagnosis of acute appendicitis is not uncommon. Rarely does infection of the triradiate cartilage imitate this entity. This case highlights an uncommon presentation of acetabular osteomyelitis as acute appendicitis and the severity of its sequelae. Like septic arthritis of the hip, acute appendicitis overtreatment is acceptable in part because of the complications resulting from delayed diagnosis and treatment. However, this case demonstrates the need to consider pelvic osteomyelitis and peripelvic infection in the differential diagnosis of appendicitis.