ENDOMETRIOSIS means, pathologically, the occurrence of endometrial-like tissue outside the limits of the mucosal lining of the uterus. Endometriosis of the vermiform appendix, although rare, is being seen with increased frequency. This type of appendical lesion may cause grave complications that can threaten the life of the patient, as will be described in a case report in this contribution. Appendical endometriosis is being more frequently recognized because both the pathologist and the surgeon have learned to identify its gross and microscopic characteristics.
Endometriosis was first reported and described by von Rokitansky1 in 1860. After this discovery, many theories were advanced to explain the occurrence of endometrial lesions in extragenital anatomic locations. These were designated as examples of "external endometriosis." In 1921 Sampson2 partially clarified this complex problem by proposing his theory of transtubal retrograde endometrial implantation at the time of menstruation. However, because proved instances of endometriosis had