Constrictive Pericarditis: This condition is characterized by a thickened, fibrotic pericardium that restricts diastolic filling of the heart, leading to symptoms such as hepatosplenomegaly (due to congestion), lymphedema (from impaired venous return), chest varices (as a result of increased venous pressure), and syncope (from reduced cardiac output). The combination of these symptoms strongly suggests a diagnosis of constrictive pericarditis.

Liver Cirrhosis: Cirrhosis can cause hepatosplenomegaly and lymphedema due to portal hypertension and hypoalbuminemia. Chest varices can occur if there is significant esophageal varice formation, and syncope might result from various complications such as hepatic encephalopathy or hemorrhage. However, the presence of chest varices and syncope might be less directly related to cirrhosis compared to other symptoms.
Budd-Chiari Syndrome: This syndrome, caused by hepatic vein thrombosis, can lead to hepatosplenomegaly, ascites, and potentially lymphedema due to obstruction of hepatic venous outflow. While less common, it could also lead to varices and, in severe cases, syncope due to decreased cardiac output from the increased pressure.

Cardiac Tamponade: Although less likely given the specific combination of symptoms, cardiac tamponade is a life-threatening condition that can cause syncope and, in some cases, hepatosplenomegaly if there is significant impairment of cardiac function leading to congestion. Lymphedema and chest varices are less typical but could occur in the context of severe cardiac dysfunction.
Pulmonary Embolism: A large pulmonary embolism could lead to syncope and, if chronic, could result in pulmonary hypertension, potentially causing hepatosplenomegaly and lymphedema. However, chest varices would be an unusual finding.

Lymphangiomatosis: A rare condition characterized by the abnormal formation of lymphatic vessels, which could potentially lead to lymphedema and, in very rare cases, involve the liver and spleen, causing hepatosplenomegaly. Syncope and chest varices would be unusual presentations but could occur in the context of significant disease.
Gorham-Stout Disease: A rare condition involving the replacement of bone with lymphatic vessels, which could potentially lead to lymphedema and, in rare instances, involve the thoracic cavity, causing chest varices. Hepatosplenomegaly and syncope could occur in advanced disease due to impaired circulation and cardiac output.