Mesothelial cysts of the round ligament simulating inguinal hernia. Report of four cases and a review of the literature.

Cysts of the mesothelial investment of the round ligament are rare and occur in women in their late third or fourth decades. They are relatively painless, mobile, may be perceived to be reducible, and should be included in the differential diagnosis of groin masses in women. Differentiation of these cysts from a small indirect inguinal hernia, with which they are frequently associated, is difficult and may be made only at the time of operation. They are likely to be less symptomatic than inguinal hernias. Cysts should not change in size with the Valsalva maneuver, although they may become more conspicuous with coughing. The clinical manifestations of cysts of the round ligament in four patients are described, along with a discussion of their embryologic and pathologic characteristics and a summary of the world literature. An embryologic mechanism of cyst formation is proposed and diagnostic criteria are presented. Symptomatic cysts of the inguinal ligament should be excised and the inguinal canal should be explored for possible associated indirect inguinal hernias. In the absence of symptoms or of a progressive increase in size, surgical removal of a cyst of the round ligament is not mandatory.