Aneurysms of the inferior vena cava John P. Sweeney, M D , Kathleen Turner, M D , and Kenneth A. Harris, M D , London, Ontario, Canada Aneurysms o f the inferior vena cava are very rare. We describe a case of a saccular aneurysm of the inferior vena cava that thrombosed after vigorous exercise. This presented as deep venous thrombosis associated with a retroperitoneal mass. Laparotomy with biopsy confirmed the benign nature of this lesion, and symptoms gradually resolved. It is hypothesized that the increased intraabdominal pressure during exercise led to the thrombosis of what is presumed to be a congenital aneurysm o f the inferior vena cava. (J VASC Sting 1990;12:25-7.) Aneurysms o f the inferior vena cava are extremely rare. A Medline search and review o f referenced articles yielded only three cases.l3 All three aneurysms were congenital in origin, fusiform in shape, and t w o revolved the inferior vena cava below the diaphragm. The current case presentation describes a saccular aneurysm o f the inferior vena cava distal to the renal veins that presented with thrombosis after vigorous exercise. CASE REPORT A 36-year-old man came to our vascular unit, 12 hours after the onset of a painful swelling and discoloration of his lower extremities. He had been vigorously digging
From the Department of Surgery and the Department of Pathology, St. Joseph's Health Centre. Reprint requests: K.A. Harris, MD, Department of Surgery, St. Joseph's Health Centre, 268 Grosvenor St., London, Ontario, Canada N6] 1V8. 24/37/19943
postholes for a prolonged period during the day. Other past history was noncontributory including the absence of previous deep venous thrombosis or suggestion of malignancy. On examination, he was found to be a mus~lar man weighing 100 kg. He had bilateral lower extremity swelling to the level of the buttock with a bluish discoloration. His lower extremities were somewhat cooler than his upper extremities. Initial laboratory investigation revealed no abnormal hematologic studies. The flat plate o f the abdomen on admission revealed a posterior abdominal mass extending over lumbar disc spaces 4 and 5. A clinical diagnosis of deep venous thrombosis involving the iliofemoral segment, and the inferior vena cava was confirmed on venography with no dye visualized in the distal vena cava. Collateral vessels were evident. The patient was admitted to the hospital, and his symptoms improved markedly with leg elevation and anticoagulation with heparin. He had residual mitd swelling of both lower extremities. Additional investigations performed while he was in the hospital included CT scanning of the abdomen (Fig. 1) revealing a retro-
Fig. 1. CT scan of the lower abdomen. Closedarrow points to inferior vena cava with no visible lumen. Open arrow points to aorta.
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Sweeney, Turner, and Harris
Fig. 2. Mass involving inferior vena cava below the renal arteries. Umbilical tapes are seen around the aorta (closed black arrow). Closed white arrow points to mass limited to inferior vena cava and right iliac vein (open white arrow).
Fig. 3. Microscopic examination o f the wall o f the aneurysms reveals disruption o f the intemal elastic membrane as well as disruption o f smooth muscle fibres. (Hematoxylin-eosin stain; original magnification × 125.) peritoneal mass at the level o f lumbar vertebrae 4 and 5 encompassing the inferior vena cava, possibly arising from the iliopsoas muscle. This was compatible with a retroperitoneal soft tissue tumor. There was no evidence o f distant metastatic disease and no other suggestion o f primary malignancy. Laparotomy was carried out to obtain a tissue diagnosis. Through a long midline incision the retroperitoneal tumor was exposed by reflecting the right colon to the midline and superiorly. The aorta and both iliac arteries
were exposed and encirded with umbilical tapes. With continued dissection the inferior vena cava was exposed and both iliac veins were identified. It became apparent that the retroperitoneal mass either totally surrounded the inferior vena cava or was part o f it. The surrounding tissues were edematous, and the right ureter was tethered to the mass. The mass measured approximately 7 cm in transverse diameter and was distinct from the psoas sheath extending from the confluence o f the iliac veins for 7 cm. (Fig. 2). Despite the edema around the inferior vena cava and ev-
Volume 12 Number 1 July 1990
idence of venous collaterization, bleeding was not excessive. The mass was encircled and totally resected with oversewing of the iliac veins. Gross pathologic examination revealed an aneurysm of the inferior vena cava with surrounding fibrosis and intramural thrombus. The wall of the blood vessel was distorted, and the lumen was filled with clot. The wall measured 4 mm in thickness, and the aneurysm sac was 7 cm in greatest transverse diameter. Microscopic examination (Fig. 3) revealed the disruption of the internal elastic membrane and disruption of the smooth muscle fibers of the wall. The normal architecture of the wall was distorted with a haphazard arrangement of cells. Congenital origin for this has been hypothesized with subsequent acute rupture of the inner layers of the aneurysm resulting in thrombosis.
DISCUSSION There have been no previously reported cases o f saccular aneurysms o f the inferior vena cava. Three previously reported aneurysms o f the inferior vena cava were o f congenital origin and were fusiform in shape) 3 T w o o f these aneurysms involved the vena cava above the diaphragm, and the third case involved an asymptomatic fusiform dilation o f the upper abdominal vena cava and hepatic veins. Venous aneurysms are extremely rare and are frequently confused with other tumors. Schatz and Fine 4 outline the pathologic findings o f focal intinlal thickening and variable changes in elastic fibers. The normal diameter o f the inferior vena cava has been d o c u m e n t e d as ranging from 1.5 to 3.7 cm, 5 therefore newly thrombosed aneurysms should be diagnosed by CT scanning. Although Zerhoruni et al.6 describe the characteristic CT appearance o f a throm' ~sed vein as "an enlarged vein with a low density lumen and a dense, sharply defined wall," the diagnosis was missed in our case because o f the underlying aneurysmal abnormality.
V e n a cava aneurysms
27
The most c o m m o n cause ofvena cava obstruction is a gravid uterus. Additional causes include tumor (most commonly renal cell carcinoma); however, any retroperitoneal or pelvic mass may mimic vena cava thrombosis. Primary tumors o f the inferior vena cava were not revealed in a literature search. Although thrombophlebitis may alert the surgeon to underlying malignancy, the clot seldomly presents as an inferior vena cava thrombosis. 7 The nature o f retroperitoneal masses should be determined by pathologic examination before treatment. Despite the tumor-like appearance o f the reported case, a benign diagnosis prevented needless chemotherapy. It is possible that this may represent a case of"effort thrombosis" o f the inferior vena cava with its underlying pathologic features. This may be contributed to by the Valsalva maneuver associated with the patient's vigorous effort, or possibly by external pressure on the vena cava wall digging postholes. REFERENCES 1. Oh KS, Dorst JP, Haroutunian LM. Inferior vena cava varix. Radiology 1973;109:161-2. 2. Moncada R, Demos TC, Marsan R, Churchill RJ, Reynes C, Love L. CT diagnosis of idiopathic aneurysms of the thoracic systemic veins. J Compt Assist Tomogr 1985;9:305-9. 3. Fumkawa T, Yamada T, Yutaka Moriy, et al. Idiopathic aneurysms of inferior vena cava: CT demonstration. J Compt Assist Tomogr 1986; 1:10. 4. Schatz IJ, Fine G. Venous aneurysms. N Engl J Med 1962;266:1310-12. 5. Marks WM, Koroblein M, Cullen PW, Kaiser JA. CT diagnosis of tumor thrombosis of the renal vein and inferior vena cava. AJR 1978;131:843-6. 6. Zerhoruni EA, Barth KH, Siegleman SS. Demonstration of venous thrombosis by computerized tomography. AJR 1980; 134: 753-8. 7. Farber SP, O'Donnell TF, Deterling, RA, Millan UG, Callow AD. The clinical implications of acute thrombosis of the inferior vena cava. Surg Gynecol Obstet 1984;158:141-4.
From the Department of Surgery and the Department of Pathology, St. Joseph's Health Centre. Reprint requests: K.A. Harris, MD, Department of Surgery, St. Joseph's Health Centre, 268 Grosvenor St., London, Ontario, Canada N6] 1V8. 24/37/19943
postholes for a prolonged period during the day. Other past history was noncontributory including the absence of previous deep venous thrombosis or suggestion of malignancy. On examination, he was found to be a mus~lar man weighing 100 kg. He had bilateral lower extremity swelling to the level of the buttock with a bluish discoloration. His lower extremities were somewhat cooler than his upper extremities. Initial laboratory investigation revealed no abnormal hematologic studies. The flat plate o f the abdomen on admission revealed a posterior abdominal mass extending over lumbar disc spaces 4 and 5. A clinical diagnosis of deep venous thrombosis involving the iliofemoral segment, and the inferior vena cava was confirmed on venography with no dye visualized in the distal vena cava. Collateral vessels were evident. The patient was admitted to the hospital, and his symptoms improved markedly with leg elevation and anticoagulation with heparin. He had residual mitd swelling of both lower extremities. Additional investigations performed while he was in the hospital included CT scanning of the abdomen (Fig. 1) revealing a retro-
Fig. 1. CT scan of the lower abdomen. Closedarrow points to inferior vena cava with no visible lumen. Open arrow points to aorta.
25
26
Joumal of VASCULAR SUKGERY
Sweeney, Turner, and Harris
Fig. 2. Mass involving inferior vena cava below the renal arteries. Umbilical tapes are seen around the aorta (closed black arrow). Closed white arrow points to mass limited to inferior vena cava and right iliac vein (open white arrow).
Fig. 3. Microscopic examination o f the wall o f the aneurysms reveals disruption o f the intemal elastic membrane as well as disruption o f smooth muscle fibres. (Hematoxylin-eosin stain; original magnification × 125.) peritoneal mass at the level o f lumbar vertebrae 4 and 5 encompassing the inferior vena cava, possibly arising from the iliopsoas muscle. This was compatible with a retroperitoneal soft tissue tumor. There was no evidence o f distant metastatic disease and no other suggestion o f primary malignancy. Laparotomy was carried out to obtain a tissue diagnosis. Through a long midline incision the retroperitoneal tumor was exposed by reflecting the right colon to the midline and superiorly. The aorta and both iliac arteries
were exposed and encirded with umbilical tapes. With continued dissection the inferior vena cava was exposed and both iliac veins were identified. It became apparent that the retroperitoneal mass either totally surrounded the inferior vena cava or was part o f it. The surrounding tissues were edematous, and the right ureter was tethered to the mass. The mass measured approximately 7 cm in transverse diameter and was distinct from the psoas sheath extending from the confluence o f the iliac veins for 7 cm. (Fig. 2). Despite the edema around the inferior vena cava and ev-
Volume 12 Number 1 July 1990
idence of venous collaterization, bleeding was not excessive. The mass was encircled and totally resected with oversewing of the iliac veins. Gross pathologic examination revealed an aneurysm of the inferior vena cava with surrounding fibrosis and intramural thrombus. The wall of the blood vessel was distorted, and the lumen was filled with clot. The wall measured 4 mm in thickness, and the aneurysm sac was 7 cm in greatest transverse diameter. Microscopic examination (Fig. 3) revealed the disruption of the internal elastic membrane and disruption of the smooth muscle fibers of the wall. The normal architecture of the wall was distorted with a haphazard arrangement of cells. Congenital origin for this has been hypothesized with subsequent acute rupture of the inner layers of the aneurysm resulting in thrombosis.
DISCUSSION There have been no previously reported cases o f saccular aneurysms o f the inferior vena cava. Three previously reported aneurysms o f the inferior vena cava were o f congenital origin and were fusiform in shape) 3 T w o o f these aneurysms involved the vena cava above the diaphragm, and the third case involved an asymptomatic fusiform dilation o f the upper abdominal vena cava and hepatic veins. Venous aneurysms are extremely rare and are frequently confused with other tumors. Schatz and Fine 4 outline the pathologic findings o f focal intinlal thickening and variable changes in elastic fibers. The normal diameter o f the inferior vena cava has been d o c u m e n t e d as ranging from 1.5 to 3.7 cm, 5 therefore newly thrombosed aneurysms should be diagnosed by CT scanning. Although Zerhoruni et al.6 describe the characteristic CT appearance o f a throm' ~sed vein as "an enlarged vein with a low density lumen and a dense, sharply defined wall," the diagnosis was missed in our case because o f the underlying aneurysmal abnormality.
V e n a cava aneurysms
27
The most c o m m o n cause ofvena cava obstruction is a gravid uterus. Additional causes include tumor (most commonly renal cell carcinoma); however, any retroperitoneal or pelvic mass may mimic vena cava thrombosis. Primary tumors o f the inferior vena cava were not revealed in a literature search. Although thrombophlebitis may alert the surgeon to underlying malignancy, the clot seldomly presents as an inferior vena cava thrombosis. 7 The nature o f retroperitoneal masses should be determined by pathologic examination before treatment. Despite the tumor-like appearance o f the reported case, a benign diagnosis prevented needless chemotherapy. It is possible that this may represent a case of"effort thrombosis" o f the inferior vena cava with its underlying pathologic features. This may be contributed to by the Valsalva maneuver associated with the patient's vigorous effort, or possibly by external pressure on the vena cava wall digging postholes. REFERENCES 1. Oh KS, Dorst JP, Haroutunian LM. Inferior vena cava varix. Radiology 1973;109:161-2. 2. Moncada R, Demos TC, Marsan R, Churchill RJ, Reynes C, Love L. CT diagnosis of idiopathic aneurysms of the thoracic systemic veins. J Compt Assist Tomogr 1985;9:305-9. 3. Fumkawa T, Yamada T, Yutaka Moriy, et al. Idiopathic aneurysms of inferior vena cava: CT demonstration. J Compt Assist Tomogr 1986; 1:10. 4. Schatz IJ, Fine G. Venous aneurysms. N Engl J Med 1962;266:1310-12. 5. Marks WM, Koroblein M, Cullen PW, Kaiser JA. CT diagnosis of tumor thrombosis of the renal vein and inferior vena cava. AJR 1978;131:843-6. 6. Zerhoruni EA, Barth KH, Siegleman SS. Demonstration of venous thrombosis by computerized tomography. AJR 1980; 134: 753-8. 7. Farber SP, O'Donnell TF, Deterling, RA, Millan UG, Callow AD. The clinical implications of acute thrombosis of the inferior vena cava. Surg Gynecol Obstet 1984;158:141-4.
