Simultaneous acute appendicitis in monozygotic twins: coincidence or genetic?

Acute appendicitis is the most common cause of an acute surgical abdomen. The authors present the first case of simultaneous acute appendicitis in monozygotic twins in the English literature and the fifth case reported in the world literature. Twin sisters, whose homozygosity is proven by DNA testing, presented with symptoms of acute appendicitis within 16 hours of each other. Both had acute appendicitis, one with free intraperitoneal perforation. These cases are presented, the world literature reviewed, and possible etiologic factors are discussed.