Lymph node enlargement in pulmonary arterial hypertension due to chronic thromboembolism.

The aim of this study was to determine the prevalence and location of enlarged mediastinal and hilar lymph nodes in patients with pulmonary arterial hypertension (PAH) due to chronic pulmonary thromboembolism (CPTE) and to identify possible causes. Thoracic CT images of 85 patients (43 men and 42 women, aged 18-80 years) with PAH in whom CPTE was confirmed at surgery (n = 75) or angiography and angioscopy (n = 10) were evaluated by two thoracic radiologists to determine the presence, size and location of lymph nodes more than 1 cm in the short axis. The presence of pleural and pericardial effusions and parenchymal abnormalities were also noted. Enlarged lymph nodes were identified in 38 patients (44.7%), including 11 with possible causes of lymphadenopathy other than CPTE. In the 27 patients with CPTE alone, 67 enlarged lymph nodes were detected (average 2.5 per patient). Nine patients had three or more enlarged lymph nodes. The most common sites of lymph node enlargement were American Thoracic Society locations 7 (n = 13), 6 (n = 10), 11L (n = 9), 10R (n = 7) and 4R (n = 7). Pleural and pericardial effusions were more common in patients with CPTE who also had lymphadenopathy than in the group with no lymphadenopathy (P < 0.05). Lymph node enlargement is common in patients with PAH caused by CPTE. The frequent association of lymphadenopathy with pleural and pericardial effusions suggest a possible pathophysiological mechanism of increased lymphatic flow caused by right heart failure.