Rare extragenital endometriosis: pathogenesis and therapy

Background: In the context of extragenital endometriosis, the gastrointestinal, urinary tract, abdominal wall, and thorax localizations are considered relatively frequent, while the umbilical, inguinal, sciatic nerve, liver, and pancreas are instead "rare". Methods: Online searches were carried out in PubMed database of the last 20 years for these terms: extragenital endometriosis, umbilical endometriosis, inguinal endometriosis, sciatic nerve endometriosis, hepatic and pancreatic endometriosis. The following exclusion criteria were used: (1) Personal surgical history unspecified. (2) Nonspecific histological diagnosis for each type of endometriosis examined. (3) Inability to distinguish between the personal series of the author and the case reports described. (4) Proceedings of scientific meetings were not included. Tables that are easy to consult were compiled. Results: 810 titles were found among which 162 studies were selected for reading in full text and finally 114 papers were included, which met the objective of the revision. The so-called "rare" forms of extragenital endometriosis show an unsuspected frequency, an extreme variability of presentation, and uncertain treatment guidelines. Discussion: Gynecologists, general surgeons, and neurologists should be well acquainted with these pathologies to avoid confusing diagnostic paths and to set up adequate therapies.