[Leiomyosarcoma of the great veins: a case involving the left iliac vein extending to the inferior vena cava].

Large veins LMS is a rare slow growing malignant tumor originating from smooth muscle cells of the media. The authors report a case of LMS of the left common iliac vein propagating to the Inferior Vena Cava that presented with a left femoral-iliac deep thrombophlebitis. CT scan showed an uneven solid mass approximately 5 cm large within the left side of the pelvis. The mass displaced the left iliac artery and compressed the left iliac vein without a significant cleavage surface between the mass itself and the vascular structures. Location was next to the spine, medially and anteriorily to the psoas muscle. A thrombosis could be noticed within the distal segment of the inferior Vena Cava and within the proximal segment of the left iliac vein. US scan with fine needle biopsy of the mass didn't yield significant information. At surgical exploration a neoplastic mass involving and blocking the left iliac vein was found. Veinotomy performed on the iliac vein and on the distal segment of the Inferior Vena Cava but without infiltration of the vein walls. Surgical treatment consisted of asportation of the neoplastic mass, resection of the left iliac vein and thrombectomy of the Inferior Vena Cava. Histologic examination of the operated specimen revealed a mixoid LMS with vascular origin without involvement of the surrounding lymph nodes. Absence of clinical and radiological signs of relapse eight months after surgery makes further surgical and complementary (drug- and radiotherapy) treatments currently unnecessary.