Appendicitis in a Spigelian hernia: an unusual cause for a tender right iliac fossa mass.

Spigelian hernias are a rare type of hernia through the Spigelian aponeurosis, whose contents commonly include omentum or small bowel. In the absence of incarceration or strangulation, they can be difficult to diagnose clinically. In the emergency setting, they can present rarely as a painful abdominal mass and computed tomography provides a reliable diagnostic imaging modality. We report an emergency presentation of a Spigelian hernia containing the appendix.