Appendicular endometriosis mimicking appendicitis

Abstract

A 31-year-old woman presented to the emergency department with right lower quadrant pain. The pain had started three days earlier with increasing intensity postprandially, when walking and in right decubitus position. Completion of her last menstruation was one week before admission. Clinical examination confirmed the right fossa pain with a negative psoas sign. Laboratory findings revealed normal white blood cell count (6.4 x 109/L) and a mild elevation of the CRP (12.6 mg/L). Abdominal ultrasound and CT showed a pathological wall thickening of the appendix extending to the caecum and with infiltration of the peri-appendicular fat and a thickening of the adjacent peritoneal membrane (Fig. A, B). There was no free fluid. Based on the clinical and imaging findings, the tentative diagnosis of appendicitis was made, and a laparascopic appendectomy and a partial caecal resection was performed. Microscopic examination of the appendix showed only minor signs of inflammation, but the presence of fibrous tissue intermixed with endometrial glandular tissue. The latter was confirmed by CK-7 and CD-10 positive staining. Delayed second-look laparascopy showed adhesion of both ovaries towards the uterus and endometriosis sites in the rectovesical excavation and the recto-uterine pouch. Retrospective analysis of the CT-images depicts the close proximity of both ovaries to the uterine body (Fig. C).