Budd-Chiari-Like Syndrome Associated with a Pheochromocytoma Invading the Right Atrium in a Dog

Rosa, C. 180 INTRODUCTION Budd-Chiari-like syndrome (BCLS) refers to hepatic venous outflow obstruction, resulting in post-sinusoidal portal hypertension and peritoneal effusion. The obstruction may occur anywhere along the post-hepatic veins, caudal vena cava (CVC), up to the right atrium (1, 2). Causes of BCLS include CVC intra-luminal obstruction (e.g., thrombosis and neoplasia) (2, 3, 4), extra-luminal compression (e.g., mass or neoplasia) (1) and kink (5), as well as, cardiac diseases (e.g., right heart failure, pericardial tamponate, constrictive pericarditis, (6) cor triatriatum dexter (7) and heartworm disease) (1, 6, 7) and miscellaneous causes including diaphragmatic hernia (8, 9). In general, post-hepatic portal hypertension most commonly originates in the hepatic veins, CVC or right atrium and is frequently caused by right heart failure, pericardial disease, liver disease, pulmonary hypertension and BCLS (1, 10, 11). The localisation of the portal hypertension site has clinical relevance, because the location of obstruction often dictates the clinical presentation (e.g., ascites, hepatic encephalopathy and multiple acquired portosystemic shunts), diagnostic evaluation (e.g., liver function tests, peritoneal fluid analysis and imaging technique) and treatment (1, 2). The peritoneal fluid in BCLS is a modified transudate (2, 11-14, 15, 16-18) with moderate cellularity (1000-7000 cells/μl) and protein concentration (2.5-7.5 g/dl) (10). It accumulates secondary to post-sinusoidal portal hypertension. The obstruction of the CVC leads to an imbalance in Starling ́s law (1), where fluid is driven into the interstitial space due to the portal hypertension, and when the capacity of the regional lymphatics is overwhelmed, ascites develops (1, 10). From a diagnostic point of view, presence of a modified transudate is non-specific. The main differential diagnoses include right heart failure, liver diseases, neoplasia and BCLS (1, 10, 11). Phaeochromocytoma is a rare cause of BCLS, and only five confirmed cases have been described previously (2, 4, 13). Only one of these has been described as extending from the adrenal gland through the CVC up to the right atrium (2). This current report describes a case of phaechromocytoma Budd-Chiari-Like Syndrome Associated with a Pheochromocytoma Invading the Right Atrium in a Dog