Thrombosis in a cavernous left-sided inferior vena cava. An unusual abdominal mass.

A 19-year-old man had an abdominal mass and swelling of the left thigh. The presumptive diagnosis was lymphoma. On exploration the mass proved to be a thrombosed multiloculated "cavernous transformation" of a venous structure, presumably the inferior vena cava, which on postoperative cavogram was shown to be otherwise absent. The venous system of the left lower extremity showed phlebographic evidence of old thrombosis, but that of the right lower extremity was normal. The patient did well without further treatment, despite some residual swelling of the left thigh. To our knowledge, this precise combination of inferior vena cava anomalies has not been encountered before; certainly not presenting as a mass.