Lumbar hemorrhagic synovial cysts: diagnosis, pathogenesis, and treatment. Report of 3 cases

To define the etiologic, clinical, histological, and surgical features of lumbar hemorrhagic synovial cysts (LHSCs). Three personal cases are reported together with a review of the pertinent literature. We identified 3 cases of LHSC treated in our departments and 20 cases culled from the literature. A total of 23 cases of LHSC were selected. All the patients underwent surgical treatment because of untreatable radicular pain and/or neurological deficits. The amount of bleeding, either massive or minor but repeated, influenced the timing of surgery. In our cases, the histological examinations showed an inflammatory reaction within the cyst and the consequent formation of neoangiogenic vessels. Hemorrhagic synovial cyst of the spine is rare and its most common localization is lumbar. Bleeding within the cyst leads to an increase of its volume, accompanied by neurological deficits and/or painful symptoms that are violent and generally intractable.