Retroperitoneal Leiomyosarcoma Invading the Inferior Vena Cava

Discussion

Leiomyosarcoma is a malignant tumor demonstrating smooth muscle differentiation occurring in the retroperitoneum in 10-20% of cases.¹ It is the second most common sarcoma in the retroperitoneum after liposarcoma.² Poorly differentiated liposarcomas contain variable amounts of fat, making it more challenging to distinguish these from leiomyosarcoma.² When leiomyosarcomas involve the IVC, they account for approximately 0.5% of adult soft-tissue sarcomas.³ Retroperitoneal masses often grow to large sizes before detection and are often detected incidentally during imaging for other indications or secondary to compressive symptoms.² Contributing to this delayed picture is the relative sparing of visceral and vascular structures; however, those affecting the vasculature often present earlier. Luminal invasion of the IVC by a retroperitoneal leiomyosarcoma can produce signs and symptoms relative to distal venous congestion. Suprahepatic invasion may lead to signs and symptoms of Budd-Chiari syndrome or right upper quadrant tenderness, while infrahepatic but suprarenal invasion may present with renal dysfunction; a patient with infrarenal invasion may demonstrate bilateral leg edema.² Finally, leiomyosarcoma with IVC involvement, regardless of location, has the potential for pulmonary embolism. Contributing to this increased risk is the hypercoagulable state seen in malignancy as well as the propensity for tumors with vascular involvement to form thrombus with subsequent embolization.

Retroperitoneal leiomyosarcomas are most commonly diagnosed using CT or MRI.⁴ Extravascular growth pattern is the most common, accounting for more than 60% of cases, while extravascular tumor growth with intravascular involvement occurs in approximately 30% of cases.⁴ Vascular involvement increases the chances of metastasis during diagnosis, with metastases seen in 9% and 23% of extravascular tumors vs tumors with intravascular involvement, respectively.⁵ Common sites of metastasis include the lung, liver, and peritoneum.

Retroperitoneal leiomyosarcomas generally demonstrate a heterogeneous pattern on CT. In tumors with vascular involvement, a relatively smaller extravascular component may suggest that the tumor originates from the IVC smooth muscle itself, whereas a large extravascular component suggests an extraluminal etiology with secondary IVC involvement. Definitive histological diagnosis is required for planning of neoadjuvant therapy.⁶ Image-guided biopsy enables the correct diagnosis, including establishing the tumor subtype.⁷

Surgical resection offers the best opportunity for survival, demonstrating a 5-year disease-free survival of 20-56%.³ In comparison, patients who do not undergo resection typically survive less than 1 year. Resectability in patients with vascular involvement depends on the tumor location and structures involved; IVC reconstruction may be an option.⁸ In patients demonstrating signs and symptoms from IVC occlusion, including downstream organ dysfunction, bridging stent placement may benefit the patient. The aim of stent placement is to improve quality of life and optimize overall preoperative patient status via restoration of vessel patency.⁹ Literature on stenting in malignant IVC syndrome is scarce, but data are promising, with reported success rates of 78-100%.¹⁰ Stent placement has risks including stent migration and vessel perforation; therefore, this primary palliative management option should be reserved for patients experiencing severe symptoms and decreasing quality of life or who could otherwise become surgical candidates with improvement of status. In patients who are not candidates for surgical resection, treatment options include chemotherapy and radiation therapy.