Intravascular lipoma of the superior vena cava
Primary tumors of the major central veins are rare and the inferior vena cava is the vein more frequently involved. Some cases of a lipoma projecting into the inferior vena cava (IVC), brachiocephalic vein, femoral vein and rarely into the superior vena cava (SVC) have been described previously [1, 2, 3]. We report a case of intravascular lipoma of the SVC in a patient without any signs or symptoms directly correlated with the tumor. Usually surgical excision is indicated only when the tumor causes pain or compression of adjacent structures. In this case, the cardiac surgeon decided to operate because of the slowing and turbulent blood flow, and subsequently thrombotic complication in the IVC and venous portal system. The clinical presentation was not clear, and the first evaluations did not lead to a well-defined diagnosis: the patient was not really symptomatic and the examination was not helpful. The CT scan was obtained to exclude pancreatitis because of the high lipase, amylase and blood glucose levels. Unexpectedly, the CT scan showed a significant intravascular thrombosis at the level of the SVC and IVC. Furthermore, the CT images revealed a suspicious gastric wall thickness, thus according to recent publications [4, 5], a paraneoplastic syndrome was believed to be the most likely diagnosis. Therefore, anticoagulant therapy was started. Laboratory analysis was ordered to obtain the tumor markers, and the EGDS and the colonoscopy were performed to exclude malignancy. The only significant examination that suggested the definitive diagnosis was the second CT scan. The anticoagulant therapy was efficacious only in the venous district of the IVC and the portal vein. This suggested that the cause of obstruction of the SVC was of a different nature. A well-executed densitometric study of the CT scan and the further investigation with MRI confirmed the presence of a lipoma. The patient was judged in need of surgical intervention since the lipoma was complicated by the thrombosis of the IVC and the portal vein.
Intravascular lipomas may be asymptomatic, incidentally revealed by imaging, or they may cause a venous obstructing or mediastinal syndromes by virtue of an excessive size causing compressive effects. This reflects the benign nature, the slow growth of the tumor and the compressibility of lipomas in general. In our case, the patient was free of symptoms or signs directly caused by the intracavallipoma. The left-sided abdominal pain, which the patient presented to the ED, may be explainable by the partial obstruction of the suprahepatic IVC and the portal vein, seen in the first contrast-enhanced CT, which both disappeared in the second CT scan after the anticoagulant therapy. Moreover, laboratory analysis during the admission revealed a low antithrombin III, which can be explained by consumption during the thrombotic event. This confirmed the thrombotic nature of filling defects previously presented in those venous districts. We postulated that the thrombosis was caused by the slowing down of blood flow in the venous districts of the IVC, due to the subtotal occlusion of the SVC. The postoperative period was free from complications, and the patient was discharged with only anticoagulant therapy for the persistent atrial fibrillation. After a follow-up of 3 months, the patient had a completely normal laboratory analysis, and there were no signs or symptoms of recurrences.
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