Primary umbilical endometriosis: case report and literature review.

We present a case of primary endometriosis of the umbilicus in a young nulliparous patient without any previous history of abdominal or pelvic surgery. Primary endometriosis of extra pelvic sites is unusual while umbilical endometriosis is quite rare. Diagnosis of endometriosis is difficult to obtain and sometimes diagnoses can be false-positive or false-negative. Some imaging procedures can be done to rule out other disorders but it is difficult to differentiate them from endometriosis. A definite diagnosis can only be established by histopathological examination. Hematoxylin and eosin (H&E) is the staining of choice. Conservative surgical excision of the lesion and drugs such as oral contraceptives and gonadotropin releasing analogues are the first-line treatment.