Growth of a leiomyosarcoma of the inferior vena cava.

Until recently, leiomyosarcoma of the inferior vena cava was rarely diagnosed preoperatively. The authors describe a patient who was treated for 12 months on the basis of a presumptive diagnosis of thrombosis of the inferior vena cava. Abdominal ultrasonography and computed tomography demonstrated interval growth, and venous biopsy revealed a malignant spindle-cell neoplasm. Surgical excision confirmed the presence of a leiomyosarcoma, which had grown slowly for at least several months before entering a phase of accelerated growth.