Neoplasm or Pseudoneoplasm? Broaden Your Differential Diagnosis Beyond Conditions Native to the Gastrointestinal Tract

Endometriosis is a benign complex gynecologic disease characterized by the presence of endometrial tissue outside the uterus. The intestines are the most common extrapelvic site affected by endometriosis, with gastrointestinal (GI) involvement reported in up to 12% of women with the disease. In the GI tract, the sigmoid colon is the most commonly involved, followed by the rectum, ileum, appendix, and cecum. Endometrial tissue usually implants in the submucosa, muscularis propria, or subserosal tissue with rare involvement of the mucosa.