title: Menstruating from the umbilicus as a rare case of primary umbilical endometriosis: a case report.
abstract: BACKGROUND
  Endometriosis is a common gynecological condition and presents mainly with involvement of the pelvic organs. Extrapelvic presentations in almost all parts of the body have been reported in the literature. However, umbilical endometriosis that is spontaneous or secondary to surgery is uncommon and accounts for only 0.5% to 1% of all endometriosis cases.
  
  
  METHODS
  A 35-year-old Caucasian woman presented with umbilical bleeding during periods of menstruation. Her umbilicus had a small nodule with bloody discharge. An ultrasound was performed and a diagnosis of possible umbilical endometriosis was thus made. The nodule shrunk in response to gonadotropin-releasing hormone analogues but continued to persist. The patient underwent a wide local excision of the nodule with a corresponding umbilical reconstruction. Histopathology confirmed the diagnosis of umbilical endometriosis. The patient was asymptomatic at follow-up, but nevertheless warned of the risk of recurrence.
  
  
  CONCLUSIONS
  Pelvic endometriosis is a common condition, but the diagnosis of primary umbilical endometriosis is difficult and differentials should be considered. This case strongly suggests that a differential diagnosis of endometriosis should be considered when an umbilical swelling presents in a woman of reproductive age.
authors.affiliation: Department of Obstetrics and Gynaecology, Wansbeck General Hospital, Woodhorn Lane, Ashington NE63 9JJ, Northumberland, UK.
authors.forename: Pallavi V
authors.initials: PV
authors.lastname: Bagade
authors.forename: Mamdouh M
authors.initials: MM
authors.lastname: Guirguis