Imatinib is partially effective for the treatment of pulmonary capillary hemangiomatosis

Clinical and Hemodynamic Responses to Imatinib in Pulmonary Veno-Occlusive Disease/Pulmonary Capillary Hemangiomatosis: A Retrospective Pilot Study of Five Cases and Review of the Literature

BACKGROUND

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are rare types of pulmonary arterial hypertension with dismal prognoses; there is no established medical treatment for these conditions. Possible efficacy of imatinib against these conditions has been reported in 15 cases; however, how and in whom imatinib is effective remain unknown.

METHODS

We retrospectively evaluated clinical data from consecutive patients with PVOD/PCH treated with imatinib at our institution. The diagnosis of PVOD/PCH was established using the following criteria: pre-capillary pulmonary hypertension; diffusion capacity of the lung for carbon monoxide < 60%; and two or more high-resolution computed tomography findings of interlobular septal thickening, centrilobular opacities, and mediastinal lymphadenopathy. The dose of pulmonary vasodilators remained unchanged during the assessment of imatinib.

RESULTS

The medical records of five patients with PVOD/PCH were reviewed. The patients were aged 67 ± 13 years, their diffusion capacity of the lung for carbon monoxide was 29 ± 8%, and their mean pulmonary artery pressure was 40 ± 7 mmHg. Imatinib was administered at 50-100 mg/day; consequently, the World Health Organization functional class improved in one patient. In addition, imatinib improved the arterial oxygen partial pressure in this and another patient (these two also experienced a decreased mean pulmonary artery pressure and pulmonary vascular resistance after imatinib usage).

CONCLUSIONS

This study indicated that imatinib improves the clinical condition, including pulmonary hemodynamics, of some patients with PVOD/PCH. In addition, patients with a certain high-resolution computed tomography pattern or PCH-dominant vasculopathy may respond favorably to imatinib.

Pulmonary capillary haemangiomatosis: a distinct entity?

Pulmonary capillary haemangiomatosis (PCH) is a rare and incompletely understood histopathological finding characterised by abnormal capillary proliferation within the alveolar interstitium, which has long been noted to share many overlapping features with pulmonary veno-occlusive disease (PVOD). But are PCH and PVOD distinct entities that occur in isolation, or are they closely intertwined manifestations along a spectrum of the same disease? The classic clinical features of both PCH and PVOD include signs and symptoms related to pulmonary hypertension, hypoxaemia, markedly impaired diffusion capacity of the lung and abnormal chest imaging with ground glass opacities, septal lines and lymphadenopathy. In recent years, increasing evidence suggests that the clinical presentation, histopathological features, genetic substrate and pathobiological mechanisms of PCH and PVOD are overlapping and usually indistinguishable. The discovery of biallelic mutations in the eukaryotic translation initiation factor 2 α kinase 4 (EIF2AK4) gene in heritable PCH and PVOD greatly advanced our understanding of the overlapping nature of these conditions. Furthermore, recognition of PCH and PVOD-like changes in other pulmonary vascular diseases and in conditions that cause chronic pulmonary venous hyper-perfusion or hypertension suggests that PCH/PVOD may develop as a reactive process to various insults or injuries to the pulmonary vasculature, rather than being primary angiogenic disorders.

Features of radiological and physiological findings in pulmonary capillary hemangiomatosis: an updated pooled analysis of confirmed diagnostic cases

Pulmonary capillary hemangiomatosis (PCH) is a very rare and refractory disease characterized by capillary angioproliferation. The updated classification of pulmonary hypertension categorizes PCH into a subgroup of pulmonary arterial hypertension (PAH) alongside pulmonary veno-occlusive disease (PVOD). However, the definitive diagnosis of PCH only with noninvasive tools remains difficult. The aim of this study was to elucidate the radiological and physiological characteristics of PCH. We searched for cases of pathologically confirmed PCH in the English literature published between 2000 and 2018. We identified 26 cases among 39 studies. Then, we extracted and evaluated the relevant clinical information in all cases with available data. On chest computed tomography (CT), ground-glass opacities (GGOs) were observed in 92% of the cases, in which poorly defined nodular pattern was the most common (88%). GGOs in a bat-wing distribution were observed in one case. Septal lines and lymph node enlargement were observed less frequently (each 19%, 12%). Seven cases (27%) had overlapping abnormalities. Diffusing capacity of the lung for carbon monoxide (DL_CO) was remarkably decreased. Alveolar hemorrhage by histological findings or bronchoalveolar lavage (BAL) was observed in seven cases. The present study showed that the most characteristic findings of CT in PCH was centrilobular GGOs with a poorly defined nodular pattern, and septal lines and lymph node enlargement were seen less frequently. Alveolar hemorrhage detected by BAL and decreased DL_CO may also be helpful to recognize the possibility of PCH like PVOD.

Use of vasodilators for the treatment of pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis: A systematic review

BACKGROUND

There are several medications available to treat pulmonary arterial hypertension (PAH): PAH-targeted drugs. However, in patients with pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis (PVOD/PCH), rare diseases that cause pulmonary hypertension, the effectiveness and safety of vasodilators, including PAH-targeted drugs, are unclear.

METHODS

We searched English-language publications listed in three electronic databases (PubMed, Cochrane Library, and the Japan Medical Abstracts Society). Reports with efficacy outcomes (survival, improvement in 6-minute walk distance, and pulmonary vascular resistance) and data on development of pulmonary edema after administration of vasodilators to patients with PVOD/PCH were selected (1966 to August 2015).

RESULTS

We identified 20 reports that met our criteria. No randomized controlled or prospective controlled studies were reported. The survival time ranged from 71 minutes to 4 years or more after initiation of vasodilators. Most of the reported cases showed an improvement in the 6-minute walk distance and pulmonary vascular resistance. Pulmonary edema was reported in 15 articles, some cases of which were lethal.

CONCLUSIONS

The present study demonstrates the potential efficacy and difficulties in the use of vasodilators in patients with PVOD/PCH; however, drawing a firm conclusion was difficult because of the lack of randomized controlled trials. Further research is needed to ascertain if vasodilator use is beneficial and safe in patients with PVOD/PCH.

Efficacy and safety of long-term imatinib therapy for patients with pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis

BACKGROUND

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) are categorized as Group 1' in the clinical classification of pulmonary hypertension. No medical therapy has been proven to be effective in patients with PVOD/PCH. Imatinib is a molecular targeted drug and was expected to be effective in patients with pulmonary arterial hypertension. We evaluated its efficacy and safety in patients with PVOD/PCH.

METHODS

In the present observational study, 9 patients with PVOD/PCH received imatinib. Clinical data including exercise capacity and hemodynamics at baseline and at follow-up were compared. Survival rate of patients treated with imatinib was compared to those of 7 patients who did not treated with imatinib.

RESULTS

Imatinib was prescribed at doses of 100-400 mg/day and was well-tolerated. At follow-up, World Health Organization functional class and brain natriuretic peptide levels significantly improved. Mean pulmonary arterial pressure was significantly reduced (from 56.8 ± 8.3 to 43.7 ± 9.0 mmHg) with preserved cardiac index. Patients were treated with imatinib for 797.2 ± 487.0 days. Seven patients (77.8%) died and 2 patients (22.2%) underwent lung transplantation. Mean survival time in patients treated with imatinib therapy was 1493.7 ± 196.3 days (95% confidence interval, 1108.9-1878.5 days), significantly longer than those without imatinib treatment (713.0 ± 258.1 days, log-rank test, P = 0.04).

CONCLUSIONS

Imatinib improved exercise capacity, hemodynamics and survival in patients with PVOD/PCH. In patients with PVOD/PCH, who have no effective medical therapy available, imatinib might function as a bridge to lung transplantation, and may become a potential therapeutic option to improve their survival.

Vasoproliferative process resembling pulmonary capillary hemangiomatosis in a cat

BACKGROUND

Pulmonary capillary hemangiomatosis is a rare, vascular obstructive disorder that uniformly causes pulmonary arterial hypertension. Clinically, pulmonary capillary hemangiomatosis is indistinguishable from primary pulmonary arterial hypertension and histology is required for definitive diagnosis. The distinctive histologic feature of pulmonary capillary hemangiomatosis is non-malignant extensive proliferation of capillaries in the alveolar septae. Vasodilator treatment of humans with primary arterial hypertension due to pulmonary capillary hemangiomatosis can result in fatal acute pulmonary edema. Computed tomography is thus critical to discern pulmonary capillary hemangiomatosis from other causes of pulmonary arterial hypertension prior to vasodilator therapy. This is the first report of a vasoproliferative process resembling pulmonary capillary hemangiomatosis in the feline species.

CASE PRESENTATION

A 15-year-old, male castrated, domestic shorthair cat presented for persistent labored breathing presumptively due to congestive heart failure despite treatment with diuretics for 7 days. Echocardiography showed evidence of hypertrophic cardiomyopathy with severe pulmonary hypertension; however, a normal sized left atrium was not consistent with congestive heart failure. Thoracic computed tomography was performed and showed evidence of diffuse ill-defined nodular ground glass opacities, enlarged pulmonary arteries, and filling defects consistent with pulmonary thromboembolism. The cat acutely decompensated after a single dose of sildenafil and was euthanized. Histopathology of the lungs showed severe multifocal alveolar capillary proliferation with respiratory bronchiolar infiltration, marked type II pneumocyte hyperplasia and multifocal pulmonary arterial thrombosis.

CONCLUSION

This is the first description in a cat of a vasoproliferative disorder resembling pulmonary capillary hemangiomatosis complicated by multifocal pulmonary arterial thrombosis. Inspiratory and expiratory ventilator-driven breath holds with angiography revealed lesions predominantly characterized by ground glass opacification and vascular filling defects with absence of air trapping. The results from this report suggest that, as in humans, the cat can develop a pulmonary capillary hemangiomatosis-like disease in which vasodilator therapy to address pulmonary hypertension may lead to fatal pulmonary edema.

Pulmonary capillary hemangiomatosis: the role of invasive cardiopulmonary exercise testing

Pulmonary capillary hemangiomatosis (PCH) is a rare form of pulmonary arterial hypertension (PAH) characterized by pulmonary capillary proliferation and pseudoinvasion of collagenous septal structures. PCH is often accompanied by veno-occlusive changes and pulmonary hypertensive arterial remodeling. The clinical and pathological diagnosis of PCH can be subtle and easily missed. Most reported cases of PCH have been associated with resting PAH. We report the cases of 3 patients who initially presented with exertional dyspnea with normal to mildly elevated resting pulmonary arterial pressures and marked intrapulmonary shunting. In all 3 patients, invasive cardiopulmonary exercise testing was suggestive of pulmonary vascular disease. Owing to abnormalities on invasive exercise testing, lung biopsies were performed; these were diagnostic of PCH, and the patients were referred for lung transplantation. We describe unique features of these 3 cases-including novel pathological findings and the presence of intrapulmonary shunting in all 3 patients-and we discuss the role of cardiopulmonary exercise testing in the evaluation of PCH.

Pulmonary capillary hemangiomatosis: a focus on the EIF2AK4 mutation in onset and pathogenesis

Pulmonary capillary hemangiomatosis (PCH) is a pulmonary vascular disease that mainly affects small capillaries in the lung, and is often misdiagnosed as pulmonary arterial hypertension or pulmonary veno-occlusive disease due to similarities in their clinical presentations, prognosis, and management. In patients who are symptomatic, there is a high mortality rate with median survival of 3 years after diagnosis. Both idiopathic and familial PCH cases are being reported, indicating there is genetic component in disease etiology. Mutations in the eukaryotic translation initiation factor 2α kinase 4 (EIF2AK4) gene were identified in familial and idiopathic PCH cases, suggesting EIF2AK4 is a genetic risk factor for PCH. EIF2AK4 mutations were identified in 100% (6/6) of autosomal recessively inherited familial PCH and 20% (2/10) of sporadic PCH cases. EIF2AK4 is a member of serine/threonine kinases. It downregulates protein synthesis in response to a variety of cellular stress such as hypoxia, viral infection, and amino acid deprivation. Bone morphogenetic protein receptor 2 (BMPR2) is a major genetic risk factor in pulmonary arterial hypertension and EIF2AK4 potentially connects with BMPR2 to cause PCH. L-Arginine is substrate of nitric oxide synthase, and L-arginine is depleted during the production of nitric oxide, which may activate EIF2AK4 to inhibit protein synthesis and negatively regulate vasculogenesis. Mammalian target of rapamycin and EIF2α kinase are two major pathways for translational regulation. Mutant EIF2AK4 could promote proliferation of small pulmonary arteries by crosstalk with mammalian targets of the rapamycin signaling pathway. EIF2AK4 may regulate angiogenesis by modulating the immune system in PCH pathogenesis. The mechanisms of abnormal capillary angiogenesis are suggested to be similar to that of tumor vascularization. Specific therapies were developed according to pathogenesis and are proved to be effective in reported cases. Targeting the EIF2AK4 pathway may provide a novel therapy for PCH.