Endometriosis of the Appendix: Two Rarely Encountered Cases and Review of the Literature

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity and musculature. Appendiceal endometriosis was first described in 1860 by von Rokitansky. The pathogenesis of endometriosis is based on three main theories: Retrograde menstruation with implantation and failure of immunologic clearance, coelomic metaplasia, and hematologic or lymphatic metastasis. A 26-year-old female patient presenting with abdominal pain no known medical history and a 50-year-old female patient presenting with menstrual irregularity without any known medical problems are presented. Histopathological examination of their appendectomy specimens revealed foci of endometriosis. Appendiceal endometriosis, while relatively uncommon in patients with endometriosis, is rare in the general population. It not only may cause symptoms of acute and chronic appendicitis but is also known to cause cyclic and chronic right lower quadrant pain, melena, lower intestinal hemorrhage, and cecal intussusception. Appendicitis should be considered in the differential diagnosis. Recognition of this benign entity is essential to avoid misdiagnosis and unnecessary aggressive management.