Primary umbilical endometriosis: a case report.

Primary umbilical endometriosis is a rare phenomenon accounting for 0,4-1,0% of extragenital endometriosis. Despite the fact that it mostly presents as a typical cyclic umbilical discharge coincidental with a palpable mass, the diagnosis is often delayed due to its low prevalence, as was seen in the presented case. The exact pathogenesis is still unclear. The golden standard for diagnosis is histopathological examination, but diagnostic tools like ultrasound, MRI or CT scan can be helpful. The differential diagnosis includes a wide range of disorders. Surgical management is the preferred treatment.