Case No. :	56
Month :	August
Year :	2003
Contributor :	Dr. Jugnu Jain.

Other Cases

A 40-year-old man presented with pain and distension of the abdomen since five to six months. The patient was non-hypertensive, non-diabetic and non-alcoholic. There was no history of weight loss / fever / loss of appetite or jaundice.

A diagnosis of tuberculous abdomen had been made at another center and the patient started on antituberculous treatment. However, there was no clinical improvement.

Routine blood investigations were within normal limits.


RADIOLOGICAL FINDINGS:

At our institution, the following radiological investigations were performed.

An ultrasound examination of the abdomen showed fusiform dilatation of the inferior venacava (IVC) with a heterogeneous soft tissue mass within (Fig.1,.2) . The mass was extending from the common iliac veins to the right atrium. Moderate ascites was noted. Color Doppler study showed flow within the mass suggesting tumoral vasculature. The right common iliac vein showed patchy flow and the left common iliac vein showed echogenic thrombus within the lumen with minimal to no flow.

Fig.1	Fig.2

Plain and post contrast CT scan of the abdomen was performed with CT angiography. It revealed a large, heterogeneously enhancing mass in the IVC with few specks of calcification within. The mass produced fusiform dilatation of the IVC (Fig.3) and extended cranially into the right atrium and caudally into the common iliac veins ( Fig.4,5). No area of necrosis was noted within the mass. There was anterior displacement of pancreas, duodenum, celiac axis and the portal vein and superior displacement of the superior mesenteric artery .No focal lesions were evident in the liver. Multiple vascular channels were seen within the mass during the arterial phase. Hypertrophied feeders were seen - mainly from the common hepatic artery and right renal artery (fig.6). Also, branches from the right upper lumbar arteries were noted to supply the mass. The left renal artery was encased and was displaced posteriorly by the mass. The hepatic veins were occluded by the mass at the site of their confluence with the IVC, resulting in a perfusion defect in the liver. Both renal veins were encased by the mass. Tiny, sub-centimeter mesenteric lymph nodes were noted with moderate degree of high density ascites ( HU 14-10).

A provisional diagnosis of a leiomyosarcoma arising from the wall of the IVC was made.

Fig.3	Fig.4
Fig.5	Fig.6

An IVCgram was also performed. This revealed obstruction of IVC and venous return via collateral circulation (Fig.7& Fig.8).

Fig.7	Fig.8

CT guided biopsy of the mass was performed (fig.9).

Fig.9

The histopathological report confirmed the mass to be the leiomyosarcoma.

DISCUSSION:

Leiomyosarcoma of the inferior vena cava is a rare malignant tumor originating from the smooth muscle of the media. Although rare, it is the most common primary malignancy of the IVC.
On MR imaging, nerve sheath tumors are isointense to hypointense on T1WI and hyperintense on T2WI. They show uniform and marked enhancement on contrast administration. Spinal schwannomas may undergo cystic degeneration. Cystic, hemorrhagic, or necrotic degeneration is seen as hyperintense and variably inhomogeneous central signal intensity on T2 WI. They rarely ever show calcifications.

The IVC is the most common site for the vascular leiomyosarcoma, although this tumor sometimes develops in smaller veins too. The tumor shows a striking preponderance for older women. Approximately 80-90% of leiomyosarcomas occur in women.

The symptoms and resectability of the tumor depend on its location and extension as well as associated thrombosis. Therefore, it is useful to divide the IVC into three segments i.e. a lower segment below the renal veins, a middle segment from the renal vein up to the hepatic veins and an upper segment from the level of the hepatic veins to the right atrium. Leiomyosarcoma of the IVC most frequently occurs in the middle segment. The tumor may be purely extrinsic or intrinsic or may have both components. The tumor tends to grow slowly - expanding along the tissue planes of least resistance. Infiltration of contiguous organs has not been reported. Hematogenous metastasis is common especially to the liver, lung and brain. IVC leiomyosarcomas are usually slow growing tumors and develop adequate collateral circulation.

Patients with leiomyosarcoma of the IVC generally have non-specific complaints such as weight loss, abdominal and back pain. Tumors involving the upper segment may give rise to varying degrees of Budd- Chiari syndrome due to hepatic vein thrombosis. Patients with the tumor involving the middle segment may present with the nephrotic syndrome if the renal vein is occluded by the tumor. Infra renal leiomyosarcomas are often dormant and may cause only venous obstruction at a later stage. If the tumor involves more than one segment of the IVC, it can give rise to a combination of signs and symptoms. Until the introduction of USG and CT, IVC leiomyosarcomas were most commonly diagnosed during laparotomy or autopsy. With the development of imaging modalities like USG, CT and MRI, preoperative diagnosis is possible. Leiomyosarcoma with extravascular development may be much more difficult to differentiate from retroperitoneal tumors compressing or invading the IVC.

The differential diagnosis of an intra-luminal mass in the IVC includes leiomyosarcoma, angiosarcoma, tumor thrombus and bland thrombus.

The final diagnosis can be made by an ultrasound or CT guided biopsy. Surgical resectability is highly dependent on the location of the tumor. Complete resection of the tumor is often possible in the lower segment. En-bloc resection is usually needed in the tumor involving the middle segment along with right nephrectomy if the renal vein is involved. If the tumor involves the upper segment, complete resection is usually not possible due to frequent extension into the hepatic veins and the right side of the heart.

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