CT Appearances And Relevant Pathological Basis Of Superior Vena Cava Syndrome Resulted From Lung Cancer

Objective To explore types of CT appearances and relevant pathological changes about superior vena cava (SVC) obstruction resulted from lung cancer. To find out anatomic segment, gross types and types of CT representations about biological modes of lung cancer resulting in superior vena cava syndrome (SVCS). To study CT features of secondary lesions from SVCS resulted from lung cancer.Materials and Methods In 51 cases with SVCS originated from lung cancer, lung cancer was surely diagnosed by pathological examinations, and SVCS was surely done by clinical materials or SVC obstruction and collateral circulation on CT or SVC venography with digital subtraction angiography (DSA). All cases were analyzed retrospectively and statistically with emphasis on gross type of lung cancer, segment and degree of SVC obstruction, CT features and pathological qualities of circumferential lesions of obstructive segment, and CT signs of secondary lesions of SVC obstruction.Results (1) CT appearances of lesions around obstructive segment of SVC involved in capsulation, compression with movement or compressiontoward left without movement and complete obstruction. 21 cases of SVC capsulation were made up of simple or main ringed capsulation (11 cases), partial ringed capsulation (5 cases) and capsulation with filling in middle layer (5 cases). SVC compression with movement was 10 cases, simple or main SVC compression toward left without movement was 15 cases, and SVC complete obstruction was 5 cases. As for extent of SVC obstruction, partial obstruction (up to 90% stenosis) of the SVC, near complete to complete obstruction (90 to 100% stenosis) of the SVC and complete obstruction of the SVC was 18 cases, 28 cases, 5 cases in order. At different degree of SVC obstruction, for simple or main SVC ringed capsulation, partial ringed capsulation, capsulation with filling in middle layer, compression with movement, simple or main compression toward left without movement, probability of them on CT was of difference (PO.05). Simple extention of lung cancer and encroachment to SVC, simple lymphonodus enlargement and amalgamation around SVC and both of the two was 7 cases, 17 cases, 27 cases in turn. (2) Lung cancer resulting in SVCS in right upper pulmonary lobe, right complete pulmonary lobe, right medium pulmonary lobe, right lower pulmonary lobe, left upper pulmonary lobe and left lower pulmonary lobe was in order 32 cases, 4 cases, 3 cases, 5 cases, 2 cases and 5 cases on CT. Central type, circumferential type (mediastinal type in right upper lobe), circumferential type (not mediastinal type in right upper lobe) was 35 cases, 12 cases and 4 cases in turn on CT. Cases of biological modes of lung cancer resulting in SVCS were the same as those of pathological qualities of SVC obstructive segment. Different gross types of lung cancer in different pulmonary lobes resulted in SVCS in different biological modes (PO.05). (3) Secondary lesions on CT of SVCS resulted from lung cancer were simple constitution and opening of collateral pathway, simple swelling of chest wall, both of the two and neither of the two. And number of them was 14 cases. 12 cases, 16 cases and 9 cases in order.With SVC obstruction at different extent, constitution and opening of collateral pathway and/or swelling of chest wall were different in shown ratio on CT (PO.05). Thrombosis (or carcinomatous thrombus) was 7 cases at the end of SVC obstructive segment resulted from lung cancer. (4) SVC stent placement were performed on 7 cases, and changes of CT appearances were patancy of SVC obstructive segment, degeneration of collateral circulation and swelling of chest wall.Conclusions Basic types of CT appearances of SVC obstruction resulted from lung cancer involve in ringed capsulation, partial ringed capsulation, capsulation with filling in middle layer, compression with movement, compression toward left without movement and complete obstruction, and the former four of them have ralationship with the extent of SVC obstruction. Lung cancer in every pulmonary lobe including central type, circumferential type (mediastinal type in right upper lobe), circumferential type (not mediastinal type in right upper lobe) results in SVCS by such biological modes as simple extention of lung cancer and encroachment to SVC, simple lymphonodus enlargement and amalgamation around SVC and both of the two at the same time. The biological modes have relationship with pulmonary lobe and gross type of lung cancer resulting in SVCS. Secondary lesions on CT of SVCS resulted from lung cancer are constitution and opening of collateral pathway, swelling of chest wall, thrombosis at the end of obstructive segment of SVC. CT shown ratio of the former two have relation with extent of SVC obstruction.