Pulmonary veno-occlusive disease complicating Felty's syndrome

Pulmonary veno-occlusive disease: an 80-year-old mystery

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension which occurs in 0.1-0.2 people per million. Its etiology is still poorly understood but is related to several risk factors. The histopathology of PVOD is characterized by intimal fibrosis narrowing or the occlusion of small pulmonary veins or venules. A definitive diagnosis requires a surgical biopsy, which is a risky procedure. Thus, the diagnosis must be based on high clinical suspicion and the results of various diagnostic tests, mainly high-resolution computed tomography, pulmonary function tests, bronchoalveolar lavage, and right heart catheterization. The definitive treatment is limited to lung transplantation. Several pulmonary arterial hypertension-specific agents may cause pulmonary edema in PVOD. However, the cautious use of such medications in selected patients, and surgical or mechanical supports, may successfully bridge patients to transplantation. Given the scant knowledge regarding this entity, future studies with a focus on elucidating the etiology and establishing the optimal treatment are required, as is further development in diagnosis.

Epidemiology of Pulmonary Arterial Hypertension

Progress in understanding the basic biology and the development of new therapies for pulmonary arterial hypertension have led to improvements in survival. This article reviews clinically important changes in the classification of the pulmonary hypertensive diseases, as well as the epidemiology of various forms of pulmonary hypertension. The risk factors for the development of pulmonary arterial hypertension, prognostic markers, and the effects of current therapies on survival are discussed.

Pulmonary Veno-occlusive Disease and Pulmonary Capillary Hemangiomatosis

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are rare causes of pulmonary hypertension, regarded by some as distinct entities. However, their presentations are similar and both are associated with poor prognoses. We therefore reviewed 38 specimens [autopsies (n=15), surgical biopsies (n=15), explants (n=7), and pneumonectomy (1 case)] from 35 patients diagnosed as either PVOD (n=30; av. age 34 y, range 4 to 68 y; 19M:11F) or PCH (n=5, av. age 42 y, ranging from 9 months to 60 years; 3M:2F) to assess their interrelationship. PCH was identified in 24 (73%) cases diagnosed as PVOD, either as perivenular foci or diffuse involvement of the pulmonary parenchyma. Other features seen in PVOD were arterial medial hypertrophy and/or intimal fibrosis (88%), hemosiderosis (79%), venulitis (12%), infarction (9%), interstitial fibrosis (sometimes as localized scars) (48%), and a mild lymphocytic infiltrate (67%). In cases diagnosed as PCH, 4 showed venous and arterial changes of PVOD. Cases with PCH also all showed a mild interstitial lymphocytic infiltrate but there was no venulitis or infarction. Capillary proliferation was particularly well demonstrated by CD34 immunostaining and predominantly involved the alveoli, but was also seen within walls of bronchi and pulmonary vessels. Our data suggest that in the majority of cases PCH represents a secondary angioproliferative process caused by postcapillary obstruction rather than a separate disease. The cause of the venous obliteration was not identified but the occasional identification of phlebitis suggests this plays a role in venous damage in some cases.

Pulmonary veno-occlusive disease

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension that mainly affects children and young adults. Its cause is unknown, although viral infections and drugs have been implicated. Patients with PVOD present with symptoms of right-sided heart failure. Radiologic examination shows prominent pulmonary arteries with Kerley B lines, pleural effusion, and mediastinal adenopathy. The definite diagnosis is made by histologic examination. Eccentric intimal fibrosis and recanalized thrombi in pulmonary veins and venules, arterialized veins, alveolar edema, and medial hypertrophy of arteries are seen on lung biopsy. No effective treatment is available; lung transplantation has been tried. The prognosis associated with PVOD is poor.