Villar's nodule: A case report and systematic literature review of endometriosis externa of the umbilicus

Umbilical endometriosis is a common manifestation of external endometriosis, representing primary or secondary endometriosis, with a typical presentation that has little variation. Laparoscopic endometrioid tissue excision can result in iatrogenic seeding to the umbilicus. Historical and physical findings are pathognomonic, thus justifying a formal name-Villar's nodule, after the initial reporting physician. Surgical intervention is recommended, but medical therapy may result in long-term symptom control with minimal malignancy risk.