A 31-year-old married Korean man with lower back pain that underwent surgery to repair a herniated intervertebral disc (HIVD) L5-S1 was transferred to our clinic because of a chest radiograph showing multiple small nodules with irregular pleural thickening in both upper lungs. The patient had no other previous diseases including pulmonary tuberculosis, chest trauma, or congenital anomaly and was an office worker with no personal or family history of exposure to drugs or smoking. Upon physical examination, the man's vital signs were stable and he appeared to be healthy. He also did not complain of any other respiratory symptoms. His chest had symmetric expansion without abnormal lung sounds. His heart beat was normal and regular, and there was no cyanosis or finger clubbing; all other findings were unremarkable. His white blood count was 9,810 cells/mm3. Prothrombin time, cardiac markers, D-dimer and arterial blood gas analysis at room air were within the normal range and no abnormal electrocardiogram readings were observed. Upon transthoracic echocardiography, mild pulmonary hypertension (systolic pulmonary artery pressure 38.3 mmHg) (Fig. 1) was detected, but LV systolic function was normal and no structural abnormality was found except for mild tricuspid regurgitation.

A chest radiograph showed small nodular densities with irregular pleural thickening in both upper lung zones (Fig. 2). A spiral computed tomography pulmonary angiogram showed no evidence of a thromboembolism, but demonstrated a markedly dilated right superior pulmonary vein without connection to the left atrium and multiple nodules, suggesting collateral vascular structures in the pleural area of both upper lung zones and in the superior segment of right lower lobe (Fig. 3). Thus, small nodular densities with irregular pleural thickening in chest radiography seemed to be collateral vascular structures on the chest CT scan. A volume rendering image showed that the right inferior pulmonary vein drained into the superior pulmonary vein through an intrapulmonary venous connection (Fig. 4). Upon undergoing a selective angiogram of right lower lobar pulmonary angiogram, the entrance of the right inferior pulmonary vein to the left atrium was found to be completely blocked, and the venous return of the right lower lobe was achieved through the right superior pulmonary vein with tortuous venous collateral complex around the right hilar region in the venous phase (Fig. 5). The patient was discharged without specific treatment on the eighth post-operative day for HIVD because he had remained asymptomatic with an unlimited exercise tolerance.

Pulmonary vein stenosis is a rare congenital disease seen in neonates and children comprises only 0.4% of all congenital heart disease cases (1). Affected patients most often become symptomatic in the first few months to years of life, and frequently have 1 or more additional cardiac anomalies. Approximately one half of patients with primary pulmonary vein stenosis have some type of associated cardiac defect (6). Primary pulmonary vein stenosis is believed to result from the abnormal incorporation of the common pulmonary vein into the left atrium in the later stages of cardiac development (1). Recent studies have documented progression from normal pulmonary venous flow patterns in a significant number of patients who later developed progressive pulmonary vein stenosis (7). The evaluation of stenotic pulmonary veins is necessary in any young patient with severe pulmonary hypertension.

Pulmonary vein stenosis in adults is even rarer, and the small number of reported cases has often been associated with mediastinal processes such as neoplasms, sarcoidosis, or fibrosing mediastinitis (23), and recently has been identified as a complication of radiofrequency ablation procedures for atrial fibrillation (4). Lung parenchyma shows interstitial edema, alveolar edema, or fibrosis, resulting from long-standing insufficient venous drainage in most pediatric patients (89). However, no definite pulmonary parenchymal abnormalities in our patient were noted. Small nodular densities with pleural thickening on chest radiograph were likely to be a collateral vascular structure on chest CT scans. A markedly dilated right superior pulmonary vein and collateral vascular structure in the superior segment of the right lower lobe without connection to left atrium on CT scan, suggests the complete compensation of anomalous venous drainage. The final diagnosis could be made by angiography. Similar to the present case, a case described as isolated pulmonary vein stenosis associated with full compensation of intrapulmonary venous drainage was reported by Saida (10). However, only a tortuous pulmonary vessel in the parahilar region of the right lung field on chest film in that study was noted, compared with collateral vascular structures in the peripheral region and dilated pulmonary vessels in the right hilar area region in our study. In addition, Saida didn't mention whether the patient had pulmonary arterial hypertension or not. To knowledge of the presence of pulmonary arterial hypertension is very important because the severity of pulmonary hypertension is part of the assessment of the condition's prognosis.

Patients with the pediatric form of congenital pulmonary vein stenosis have a very poor prognosis. Survival to adulthood without treatment rarely occurs because the symptom emerges in infants with accompanying progressively worsening pulmonary hypertension (5). The prognosis depends on the severity of the associated cardiac disease and the number of the stenosed pulmonary veins (7). The cause of death is usually a pulmonary hypertensive crisis, recurrent pulmonary infection, or massive hemoptysis. Although the precise natural history of milder forms of congenital pulmonary vein stenosis is not entirely clear, patients with only 1 or 2 pulmonary veins involved have a significantly more benign course. Breinholt (7) found a mortality rate of 83% in pediatric patients with 1 or 2 stenosed pulmonary veins. Our patient has no cardiac anomaly in spite of mild pulmonary hypertension and only a single pulmonary vein stenosis with collateral circulation. Thus, we consider that our patient would have a better prognosis. To our knowledge, asymptomatic patients with isolated pulmonary vein stenosis associated with chronic compensation through venous collateral drainage have been very extremely rare, and our patient is to date the oldest adult among those with a diagnosis of pulmonary vein stenosis. More asymptomatic patients of isolated pulmonary vein stenosis with chronic compensation could be diagnosed as a result of increased awareness and improvements in noninvasive imaging modalities.