Pheochromocytoma (PCC) and paraganglioma (PGL) are uncommon tumors. Clinical manifestations are mass effect or hormone secretion. The initial manifestation with pericardial effusion is rare. The author presented a case of anterior mediastinum paraganglioma presenting with pericardial effusion two years before symptoms of catecholamine excess. This is the first case reported in Thailand. A 34 year-old female patient presented with dyspnea. There was pericardial effusion from echocardiography was diagnosed with no definite causes of pericardial effusion. After treatment with ibuprofen, pericardial effusion was absolutely resolved from repeated echocardiography. Two years later, she had headache and hypertension. Chest X-ray, there was an anterior mediastinal mass. Her 24 hours urine metanephrine was very high. By imaging, an anterior mediastinal mass was observed from CT chest without adrenal mass from CT abdomen. The result of metaiodobenzylguanidine (MIBG) scan was compatible with paraganglioma. Symptoms of headache and hypertension disappeared after surgical removal of the mass. Pericardial effusion may be the first manifestation of paraganglioma especially if the patient had hypertension or could not find the etiology. Thus, pericardial effusion should be investigated for paraganglioma. Due to long term follow-up, this indolent growing tumor may respond to NSAIDs or regress spontaneously.

Keywords: Pheochromocytoma (PCC), Paraganglioma (PGL), Metaiodobenzylguanidine (MIBG), Nonsteroidal anti-inflammatory drugs (NSAID), Pericardial effusion