Lateral cutaneous nerve entrapment syndrome associated with appendicitis.

A man in his 60s presented with localized right flank pain. Physical examination revealed a discrete tender point and a positive pinch sign. A trigger-point block led to immediate pain relief. Based on these findings, he was clinically diagnosed with lateral cutaneous nerve entrapment syndrome (LACNES). His Alvarado score was 7 and abdominal computed tomography revealed appendiceal swelling and surrounding fat stranding, indicating underlying appendicitis. The patient underwent emergency laparoscopic appendectomy. He made a full recovery with no recurrence of the pain. In this case, we speculate that appendicitis and localized peritonitis might have caused entrapment of the lateral cutaneous nerve as a result of muscle guarding. In patients with localized flank pain resembling LACNES, clinicians should not overlook the possibility of underlying intra-abdominal inflammatory conditions such as appendicitis.