Answer is B (Small cell carcinoma): Current Critical Care Diagnosis & Treatment 3ra /465 The incidence of superior vena caval syndrome is highest with small cell carcinoma. Superior vena caval syndrome (SVC syndrome) SVC syndrome results from an impedance in outflow from superior vena cava due to external compression The most common cause of SVC syndrome is external compression by a malignant tumoure The most common malignant tumor causing SVC syndrome is bronchogenic carcinomas The most common histological type of bronchogenic carcinoma causing SVC syndrome is small cell carcinomas Etiologies of Superior Vena Cava Obstruction: Malignancy 95% Lung Cancer 65% Lymphoma 15% Breast cancer 5% Germ-cell 2% Thymic cancer 2% Other cancer 4% Benign 5% Central venous device related Mediastinal fibrosis 1% 3%