Pulmonary veno-occlusion--an immune complex disease?

Diagnosis and management of pulmonary veno-occlusive disease

INTRODUCTION

Pulmonary veno-occlusive disease (PVOD) is an orphan disease and uncommon etiology of pulmonary arterial hypertension (PAH) characterized by substantial small pulmonary vein and capillary involvement.

AREAS COVERED

PVOD, also known as 'PAH with features of venous/capillary involvement' in the current ESC/ERS classification.

EXPERT OPINION

In recent years, particular risk factors for PVOD have been recognized, including genetic susceptibilities and environmental factors (such as exposure to occupational organic solvents, chemotherapy, and potentially tobacco). The discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD has been a breakthrough in understanding the molecular basis of PVOD. Venous and capillary involvement (PVOD-like) has also been reported to be relatively common in connective tissue disease-associated PAH (especially systemic sclerosis), and in rare pulmonary diseases like sarcoidosis and pulmonary Langerhans cell granulomatosis. Although PVOD and pulmonary arterial hypertension (PAH) exhibit similarities, including severe precapillary PH, it is essential to differentiate between them since PVOD has a worse prognosis and requires specific management. Indeed, PVOD patients are characterized by poor response to PAH-approved drugs, which can lead to pulmonary edema and clinical deterioration. Due to the lack of effective treatments, early referral to a lung transplantation center is crucial.

An Autopsy Case of Pulmonary Capillary Hemangiomatosis with an Electron Microscopy Study

BACKGROUND Pulmonary capillary hemangiomatosis (PCH) and pulmonary veno-occlusive disease (PVOD) are rare diseases that share clinical, X-ray, and histological features. Most patients have poor prognosis due to severe respiratory impairment. Recently, EIF2AK4 mutations were found in some patients with PCH and PVOD, but the role of this mutation is still unknown. We report an autopsy case of PCH and discuss a mechanism of respiratory dysfunction based on an electron microscopy study. CASE REPORT The patient was a Japanese man in his sixties. He suffered from acute exacerbation of dyspnea during treatment of COPD. Respiratory function testing revealed DLCO' 32.1% and DLCO'/VA 23.6%. Echocardiography demonstrated findings consistent with pulmonary hypertension. A CT scan showed mild emphysema and small ground-glass opacity in the lungs. However, we could not find the exact cause of his respiratory failure and he died 28 days after admission. At autopsy, the histology showed multilayering capillary proliferation within the alveolar walls. Electron microscopy examination revealed prominent widening of the air-blood barrier, scarce fusion of the epithelial and capillary basement membranes, and frequent narrowing of the capillary lumen. CONCLUSIONS We reported an autopsy case with PCH with no histological findings of PVOD. Whether PCH and PVOD are 2 different histological patterns of the same disease remains to be verified. The changes in the air-blood barrier detected by electron microscopy may explain the respiratory impairment and pulmonary arterial hypertension.

Pulmonary arterial hypertension in systemic lupus erythematosus: current status and future direction

Pulmonary arterial hypertension (PAH) is commonly associated with connective tissue diseases (CTDs) including systemic sclerosis and systemic lupus erythematosus (SLE). The prevalence of PAH in SLE is estimated to be 0.5% to 17.5%. The pathophysiology of PAH involves multiple mechanisms from vasculitis and in-situ thrombosis to interstitial pulmonary fibrosis which increases pulmonary vascular resistance, potentially leading to right heart failure. Immune and inflammatory mechanisms may play a significant role in the pathogenesis or progression of PAH in patients with CTDs, establishing a role for anti-inflammatory and immunosuppressive therapies. The leading predictors of PAH in SLE are Raynaud phenomenon, anti-U1RNP antibody, and anticardiolipin antibody positivity. The first-line of diagnostic testing for patients with suspected SLE-associated PAH (SLE-aPAH) involves obtaining a Doppler echocardiogram. Once the diagnosis is confirmed by right heart catheterization, SLE-aPAH patients are generally treated with oxygen, anticoagulants, and vasodilators. Although the prognosis and therapeutic responsiveness of these patients have improved with the addition of intensive immunosuppressive therapies, these treatments are still largely unproven. Recent data put the one-year survival rate for SLE-aPAH patients at 94%. Pregnant women are most at risk of dying due to undiagnosed SLE-aPAH, and screening should be considered essential in this population.

Pulmonary veno-occlusive disease: the bête noire of pulmonary hypertension in connective tissue diseases?

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension that may develop in patients with connective tissue diseases (CTD). Most cases have been reported in patients with systemic sclerosis, though associations with systemic lupus erythematosis and mixed connective tissue disease have also been described. PVOD is characterised by progressive obstruction of small pulmonary veins and venules that leads to increased pulmonary vascular resistance, right heart failure and premature death. Distinguishing PVOD from pulmonary arterial hypertension (PAH) is often difficult, though use of a diagnostic algorithm may improve diagnostic accuracy and preclude recourse to lung biopsy. The finding of normal left-heart filling pressures in the context of radiological studies suggestive of pulmonary oedema is an important diagnostic clue, particularly if this clinical scenario coincides with the introduction of vasodilator therapy. There are no approved treatments for the disorder, though cautious use of PAH specific therapy may improve short-term outcomes in selected idiopathic PVOD cases. This review summarises the epidemiologic, clinico-pathologic and imaging characteristics of PVOD in the setting of CTD and discusses potential management approaches.

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.

Vascular Toxicity of Antineoplastic Agents

Among the various deleterious effects of cancer chemotherapy, vascular toxicity is the least well recognized. This lack of recognition may be because the vasculotoxic phenomena are not unique to antineoplastic agents, can occur in patients without exposure to these agents, and the fact cancer itself may produce a hypercoagulable state. As a result, many vascular events either go unnoticed, are ignored, and/or are attributed to the underlying malignancy. Many antineoplastic therapies are associated with various vascular phenomena that range from simple phelibitis to lethal microangiopathy. Recognition of these events is important to minimize the morbidity and even prevent unnecessary deaths. Herein we review the vascular syndromes that have been reported in association with antineoplastic agents.

Pulmonary veno-occlusive disease caused by an inherited mutation in bone morphogenetic protein receptor II

Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension in which the vascular changes originate in the small pulmonary veins and venules. The pathogenesis is unknown and any link with primary pulmonary hypertension (PPH) has been speculative. Mutations in the bone morphogenetic protein receptor II (BMPR2) gene have been identified in at least 50% of familial cases and in 25% of sporadic cases of PPH. We report a patient with documented PVOD whose mother had severe pulmonary hypertension. Sequencing of the patient's BMPR2 coding region revealed a del44C mutation in Exon 1 that is predicted to encode for a truncated protein. Analysis of DNA from family members suggests that this mutation was transmitted by the proband's mother to two of her four children. The finding of PVOD associated with a BMPR2 mutation reveals a possible pathogenetic connection with PPH.

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.

Pulmonary veno-occlusive disease presenting with thrombosis of pulmonary arteries

Pulmonary veno-occlusive disease is a rare cause of pulmonary hypertension. An unusual case presenting with thrombosis of the right pulmonary artery and serological evidence of autoimmunity is reported.

Pulmonary veno-occlusive disease: diagnosis during life in four patients

Pulmonary veno-occlusive disease is a rare form of primary pulmonary hypertension of unknown aetiology. Four cases were diagnosed in young patients. The diagnosis was suspected on the basis of clinical, radiological, echocardiographic, and catheter evidence and confirmed by taking a lung biopsy sample. In all patients the histology showed obstruction of the pulmonary veins by intimal fibrosis. The clinical course of all patients has been one of progressive deterioration. Although there is no specific treatment for this disease, to establish the diagnosis during life is of great importance in overall clinical management, including counselling the patient and family.

Pulmonary veno-occlusive disease. Fatal progression of pulmonary hypertension despite steroid-induced remission of interstitial pneumonitis

This report describes a 28-yr-old patient with pulmonary veno-occlusive disease (PVOD). She presented with pulmonary hypertension, hypoxemia, and interstitial pneumonitis. We report the discordance between the response of her hypoxemia and interstitial pneumonitis, which resolved with corticosteroid therapy, and her progressive pulmonary hypertension, which caused fatal right heart failure. This report emphasizes that the radiographic interstitial shadowing of PVOD may be caused by either (1) an inflammatory interstitial pneumonitis (which may be responsive to anti-inflammatory therapy) or (2) interstitial pulmonary edema, or both.

Pulmonary veno-occlusive disease following therapy for malignant neoplasms

We report three cases of pulmonary veno-occlusive disease which developed following treatment for malignant neoplasms. Two patients received single agent BCNU chemotherapy for malignant gliomas. The third patient underwent combination radiation and chemotherapy for Hodgkin's disease. Isolated case reports of pulmonary veno-occlusive disease following therapy for malignant disease are reviewed and clinical features summarized. Pulmonary veno-occlusive disease in this setting is thought to be rare. However, the diagnosis is rarely suspected clinically and is difficult to diagnose pathologically. Therefore, the true incidence of this complication is unknown and may be higher than believed. It is important that both clinician and pathologist be aware of this entity; otherwise, elastic tissue stains may not be performed and the diagnosis missed.

Pulmonary veno-occlusive disease. A report of four cases

Four cases of pulmonary veno-occlusive disease are described. Two patients, who were brothers, had respiratory tract infections. The third patient had chronic active hepatitis and coeliac disease suggesting an abnormality of the immune system; the fourth patient had no obvious cause but presented initially with systemic hypertension. Three of the cases had been diagnosed initially as primary pulmonary hypertension either on open lung biopsy or clinically. In all cases the pulmonary arteries were abnormal with medial hypertrophy, intimal fibrosis and, in some cases, thrombosis in elastic pulmonary arteries. These findings suggest that pulmonary veno-occlusive disease is not confined to veins and should be considered as a widespread pulmonary vascular disease. The range of aetiological factors indicate that it should not be considered as a single disease entity.

Congenital unilateral pulmonary venous atresia with pulmonary veno-occlusive disease in contralateral lung: an unusual association

A patient presenting with the rare association of congenital unilateral pulmonary venous atresia in one lung and pulmonary veno-occlusive disease in the other is described. The patient first presented at the age of 3 1/2 years with anemia, hemoptysis, and pulmonary hypertension. After cardiac catheterization and angiocardiography, a diagnosis of atresia of the left pulmonary veins was made for which left pneumonectomy was done. Four years later the patient presented with right-sided congestive failure and radiologic evidence of right-sided pulmonary edema from which death resulted. At autopsy, the right lung showed changes of pulmonary veno-occlusive disease, while the major veins were not involved.

Pulmonary veno-occlusive disease: involvement of pulmonary arteries and review of the literature

Pulmonary vessels from 26 patients with pulmonary veno-occlusive disease were studied histologically and morphometrically. In addition to the well-known obstruction of veins and venules, pulmonary arteries were also narrowed or obliterated in approximately half of the patients. It is unlikely that the arterial intimal fibrosis, which was sometimes as severe as the fibrosis in the veins, was secondary to the venous obstruction; rather, like the venous alterations, it probably resulted from organization of thrombi. It is possible that primary damage to the vascular wall elicited thrombosis. Such an injury may also have caused the arterialization of the venous walls, a common finding that cannot always be explained by distal narrowing of larger veins. Although the etiology of pulmonary veno-occlusive disease is obscure, it seems increasingly likely that multiple noxious agents may induce this condition. In children no predilection for either sex has been observed, but in adults, men are affected twice as often as women.

Fine structural changes in cryptogenic fibrosing alveolitis and asbestosis

Lung biopsies from 17 patients with cryptogenic fibrosing alveolitis of a cellular rather than fibrotic pattern were examined by transmission electron microscopy in the hope that such cases would show features of pathogenetic significance. Further selection was made by choosing minimally affected areas. There was no ultrastructural evidence of immune complex deposition but alveolar epithelial and capillary damage was frequently found (17 and 14 of the 17 cases respectively). Alveolar epithelial injury consisted of patchy necrosis and regenerative hyperplasia. Alveolar capillary injury consisted of cytoplasmic swelling and basement membrane thickening and reduplication. Many of these features have not been emphasized in previous reports and their prominence in early stages of the disease suggest that they may have pathogenetic significance, possible mechanisms of which are discussed. Similar findings identified during the course of this study in 8 asbestos workers suggest that similar pathogenetic mechanisms may operate in asbestosis.

Pathologic pulmonary alterations in long-term human heart-lung transplantation

Twenty-one patients with end-stage pulmonary hypertension underwent combined allograft heart-lung transplantation after 1980. Almost 80 per cent of these patients survived beyond the immediate postoperative period, with the longest survival period more than 3 1/2 years at the time of this report. Five patients died in the perioperative or immediate postoperative period, and 11 returned to normal lives with essentially normal pulmonary function. In the remaining five allograft recipients recurrent respiratory infections and progressive obstructive airway disease developed, with superimposed restrictive deficits in three of them. Two open lung biopsies, two autopsies, and one retransplantation were performed in these recipients. Morphologically, these allograft recipients showed extensive bronchiolitis obliterans, interstitial and pleural fibrosis, and accelerated arterial and venous arteriosclerosis. Bronchiolitis obliterans may prove to be a significant complication of heart-lung transplantation.

Pulmonary veno-occlusive disease after bone marrow transplantation

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Immunopathologic and clinical studies in pulmonary hypertension associated with systemic lupus erythematosus

PH is an uncommon manifestation of SLE. The symptoms of PH develop within a few years after the onset of the multisystem disease. The most common presenting complaints of SLE patients with PH are dyspnea on exertion, chest pain, nonproductive cough, edema, and fatigue or weakness. The important physical findings are a loud second pulmonic heart sound and a right ventricular lift. The chest roentgenogram shows a cardiomegaly, a prominent pulmonary segment, and usually clear lung fields. Pulmonary function tests may show evidence of restrictive lung disease; however, the physiologic abnormalities are mild and out of proportion to the severity of the PH. The diagnosis of PH is established by cardiac catheterization showing elevated pulmonary artery pressure, normal capillary wedge pressure, and no evidence of intracardiac or extracardiac shunts. Pathologic examination of the lung demonstrates angiomatoid lesions involving muscular pulmonary arteries. There is a thickening of the media and subintima of the arterioles. Immunoglobulin and complement deposits are found in the walls of pulmonary arteries. Immunoglobulin eluted from the lung contains rheumatoid factor and antinuclear antibody including antibody to DNA activity. DNA antigen is also present in walls of blood vessels. These results suggest an immune complex deposition process as a mechanism in the pathogenesis of PH in SLE. The clinical course of PH in SLE is variable. Symptoms may be mild and the disease follows a stable and protracted course for several years. It can, however, develop a progressive course ending in death in a few years. The clinical response of SLE patients with PH to treatment with high doses of systemic corticosteroids is not consistent or predictable.

Applications of electron microscopy to diagnostic pulmonary pathology

Viruses and other possible causative agents should be sought light and electron microscopically in all cases of ill-defined diseases including "sarcoid." Ideally, tissue should be prepared for electron microscopic examination as soon as a specimen is obtained; however, when this has not been done, tissue preserved in formalin solution can be used. Viruses, some bacteria, and other agents suspected on the basis of light microscopic findings can be verified electron microscopically by reprocessing paraffin-embedded tissue from areas that show smudge cells, focal necrosis with atypical cellular proliferation, and nuclear inclusions. Electron microscopically, all dying cells show swelling and rupture of cellular organelles and membranes; reactive changes include proliferation of branching tubules and paracrystalline and other types of proteinaceous precipitates (inclusions) in both the nucleus and cytoplasm. Qualitative and quantitative changes of cellular organelles, fibrils, microvilli, and intercellular junctions reflect hyperplasia, metaplasia, or dysplasia of the cell and may enable identification of the diseases, e.g., desquamative interstitial pneumonia. In various conditions, basal laminae become irregular, disruptive, or reduplicated following epithelial necrosis and regeneration. Electron microscopic evidence of immunologic damage to basal lamina and cells and immuno-electron-microscopic features of the lung in general require further studies. Electron microscopic features of transbronchial biopsy specimens may be diagnostic in cases of alveolar proteinosis, histiocytosis X, and amyloidosis. Ultrastructural abnormalities of cilia are common; primary ciliary defects are rare. Finally, light microscopic, scanning electron microscopic, and x-ray energy-dispersive spectrometric examinations of paraffin-embedded sections appear most practical for the pathologic evaluation of cases of pneumoconiosis.

Ultrastructure of lung in pulmonary veno-occlusive disease

A 17-year-old boy died of severe pulmonary hypertension due to pulmonary veno-occlusive disease. The condition was diagnosed in a lung biopsy specimen and confirmed at necropsy. The lung specimen was studied by electron microscopy and immunofluorescence microscopy. The occluded pulmonary veins were lined by intact endothelial cells, beneath which was a haphazard proliferation of collagen fibrils and smooth muscle cells. The alveolar capillaries showed thickening of the endothelial cell basement membrane with an increase in the number of cytoplasmic processes of pericytes. Electron-dense deposits were located within the thickened basement membrane. These deposits were considered to represent disintegrating extravasated erythrocytes rather than immune complexes because immunofluorescence microscopy showed no immunoglobulin or complement deposition within the lung.

Pulmonary veno-occlusive disease after chemotherapy

A case of pulmonary veno-occlusive disease (PVOD) in a 41-year-old woman who had received chemotherapy (bleomycin, mitomycin-C, and cis-platinum) for metastatic cervical carcinoma is reported. Before her death, pulmonary hypertension and right ventricular heart failure had been attributed to lung toxicity induced by chemotherapy, but the postmortem findings were characteristic of PVOD. The authors support the view that PVOD is a syndrome, not a distinct entity, and present the case as a further example of the many situations in which PVOD can arise. Whether the lesions of the pulmonary veins developed as a result of the chemotherapy or whether the two conditions were associated by chance must remain, for now, a subject of speculation. Pathologists are urged to devote special attention to the examination of the pulmonary vessels in patients who have received chemotherapy.

Pulmonary veno-occlusive disease in siblings: case reports and morphometric study

Two cases of fatal veno-occlusive disease are described: the first in a boy 14 years old and the second in his sister, who died, at age 13, only a few months later. In both, the first symptom was effort-induced dyspnea and the course of the disease was rapid. The chest radiograph of the boy showed diffuse opacities, whereas that of the girl showed Kerley lines bilaterally. In both, at autopsy, a diagnosis of severe veno-occlusive disease was confirmed, with partial or complete occlusion of much of the pulmonary venous bed by organized thrombi. The pulmonary vascular system of the girl was processed for light microscopic morphometry by injection of radiopaque medium into the veins of one lung and the arteries of the other. Although there was little filling of the venous system, much of the arterial system filled down to the capillary level. Pre-acinar and intra-acinar arteries showed medial hypertrophy and extension of smooth muscle into precapillary arteries. The concentration of patent intra-acinar arteries relative to alveoli was not significantly less than normal, whereas the concentration of veins was strikingly reduced. Possible pathogenetic mechanisms are discussed.

A case of congestive cardiomyopathy. Demonstration at the Royal College of Physicians of London

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Familial pulmonary veno-occlusive disease: a case report

A case of pulmonary veno-occlusive disease in a male infant who died at the age of 3 months is presented. Both intra- and extrapulmonary veins were involved. Two years earlier a brother had died of the same disease at the age of 8 weeks, but, in that case, the disease was restricted to the intrapulmonary veins. It is suggested that the disease may have been caused by a viral infection, the mother acting as a carrier. The simultaneous occurrence of intra- and extraparenchymal pulmonary vein occlusion indicates that some instances of isolated extraparenchymal pulmonary vein atresia or obstruction may also have been examples of pulmonary veno-occlusive disease.

A case of pulmonary veno-occlusive disease respondong to treatment with azathioprine

Histological features of a lung biopsy specimen from a 46-year-old woman showed all the characteristics described in veno-occlusive disease. The clinical features, however, were distinctive in that in addition to the lung involvement there was alopecia, digital vasculitic ulcers, Raynaud's phenomenon, polyarthritis, and muscle weakness. Treatment with azathioprine resulted in a progressive improvement in her condition. It is suggested that pulmonary small vein occlusion may occur as a pattern of tissue response in more than one situation and that is sometimes more amenable to therapy than has been previously reported.

Pulmonary veno-occlusive disease. Entity or syndrome?

Pulmonary veno-occlusive disease is a rare and usually fatal condition in which there is gradual obliteration of the pulmonary veins and venules. Without a lung biopsy the clinical diagnosis of this disease is difficult. If there is pulmonary hypertension with roentgenographic signs of pulmonary edema and of congestion in the absence of signs of increased left atrial pressure, the diagnosis must be considered. The morphologic picture of the lungs is characteristic. The small veins, and sometimes also the major veins, are narrowed or occluded by fibrous tissue, almost certainly on the basis of organized thrombi. Nodular areas of congestion, interstitial fibrosis, and pneumonitis are regularly present. A viral etiology has been suggested in a number of cases. If we may assume, however, that thrombosis of pulmonary veins is the initial event, the possibility has to be considered that this may be elicited by a virus in some patients and by toxic factors or by clotting disorders in others. Pulmonary veno-occlusive disease might then well be a syndrome rather than an etiologic entity.