Catamenial Bernard-Horner's syndrome related to thoracic endometriosis.

We describe the case of a young woman with a recurrent right Bernard-Horner's syndrome associated with the onset of intermittent supraclavicular mass. Surgical excision of the mass revealed the endometrial pattern of the tumor and the close relationship between Bernard-Horner's syndrome and thoracic endometriosis. No other case of this syndrome has been reported in the literature.