we have come across a case of superior vena cava syndrome ( svcs ) causing pseudolesion in segment iv of the liver . the superior vena cava ( svc ) obstruction in this case was due to bronchogenic carcinoma and the pseudolesion mimicked a secondary . if not diagnose accurately , it may lead to a liver biopsy for confirmation ; therefore , recognition of this lesion is essential . a 50-year - old female patient presented with dyspnea , chest pain for a duration of 8 months and was not responding to antibiotic therapy . a chest x - ray was advised which revealed a rounded nodular opacity in the right lung [ figure 1 ] . considering the age of the patient , possibility of malignancy was considered and the patient was further investigated with computed tomography ( ct ) of the thorax . ct revealed heterogenous enhancing lobulated mass in the superior mediastinum compressing and occluding the svc [ figure 2 ] . right middle lobe bronchus revealed cutoff sign with a moderately enhancing mass [ figure 3 ] . the metastatic mediastinal lymphadenopathy was encasing the right pulmonary artery [ figure 4 ] . multiple chest wall and suprascapular collaterals , liver examination on plain ct of the abdomen scan showed no obvious lesion . on arterial phase , a wedge - shaped hyperattenuated area in segment iv a [ figure 5 ] this finding was not visualized in venous or delayed phases . in view of scv obstruction and a wedge - shaped intensly enhancing hepatic lesion , a possibility of a pseudolesion secondary to opening of the collateral channels through vein of sappey was considered . chest x - ray showing two large nodular opacities along the right heart border axial computed tomography of the thorax ( mediastinal window ) revealed heterogenous enhancing lobulated mass in superior mediastinum compressing and occluding the superior vena cava axial computed tomography of the thorax ( a ) lung window ( b ) mediastinal window showing a right middle lobe bronchus cutoff sign due to a moderately enhancing mass . pleural and pericardial deposits along with right pleural effusion are also seen axial computed tomography of the thorax ( mediastinal window ) showing metastatic mediastinal lymphadenopathy which is encasing the right pulmonary aorta ( a and b ) axial computed tomography ( arterial phase ) showing a wedge - shaped intensly enhancing area in segment iv a the important causes of svcs are malignancy ( lung cancer ) , metastatic spread , inflammation leading to fibrosis and mediastinal masses . in svcs , ( 1 ) azygos  hemiazygos  accessory hemiazygos system  if the level of scv obstruction is above the azygos arch , antegrade flow from the azygos to the right atrium is seen , with abrupt transition between a densely opacified azygos above the arch and a unopacified inferior azygos vein . if the obstruction is below the arch , the entire azygos and hemiazygos veins are brightly opacified as the blood flows in a retrograde fashion toward the inferior vena cava . in our case ( 2 ) vertebral and subscapular plexuses  visualization of paravertebral , intervertebral , and epidural veins leading to the azygos system is observed . in our case , ( 3 ) mediastinal venous plexus and esophageal venous plexus and diaphragmatic venous plexus  in our case , no esophageal collaterals were seen . ( 4 ) lateral thoracic and superficial thoracoabdominal venous plexuses  the internal thoracic veins and lateral thoracic veins communicate with thoracoepigastric and superficial epigastric veins . chest wall and breast collateral veins can also brightly opacify as a sign of scv obstruction . internal and external mammary pathway includes internal mammary , superficial veins of the thorax , superior and inferior epigastric veins . these specific vascular collateral channels cause pseudolesion in the liver in case of scv obstruction . small vein in the falciform ligament draining anterior part of the abdominal wall into the liver will get opacified and will cause pseudolesions . these small veins have three subgroups : superior and inferior vein of sappey , vein of burow . the superior vein of sappey drains upper part of falciform ligament , medial diaphragm and enters peripheral portal branch of the left hepatic lobe . in scv obstruction , blood proximal to obstruction reaches liver through the internal thoracic , superior epigastric , and superior vein of sappey . when this channel opens up , pseudolesion becomes obvious on ct examination . in our case , intensly enhancing area in segment iv was seen . recognization of the pseudolesions in the liver is important as it can avoid wrong diagnosis of a hepatic metastasis and further unnecessary biopsy . furthermore , its detection can direct our thinking about a possible obstruction of proximal major thoracic vessels .
one of the common causes of superior vena cava ( svc ) syndrome is malignancy of the lung . 
 the invasion of svc leads to opening of the various venous channels for continuation of the blood flow from upper extremity and proximal trunk and finally draining into right atrium . 
 vein of sappey is one of these channels and it causes focal striking enhancement in segment iv of the liver on arterial phase of contrast computed tomography ( ct ) . 
 this enhancement causes diagnostic difficulty and unnecessary biopsy due to misinterpretation of it as a secondary from lung cancer . 
 awareness and accurate diagnosis can avoid further examination in such patients . 
 it can also provide an idea of a more proximal major thoracic vessel obstruction if first detected on ct of the abdomen ( contrast ) .