Pulmonary Capillary Hemangiomatosis Research Articles

Functional validation of EIF2AK4 (GCN2) missense variants associated with pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a disorder with a large genetic component. Biallelic mutations of EIF2AK4, which encodes the kinase GCN2, are causal in two ultra-rare subtypes of PAH, pulmonary veno-occlusive disease and pulmonary capillary haemangiomatosis. EIF2AK4 variants of unknown significance have also been identified in patients with classical PAH, though their relationship to disease remains unclear. To provide patients with diagnostic information and enable family testing, the functional consequences of such rare variants must be determined, but existing computational methods are imperfect. We applied a suite of bioinformatic and experimental approaches to sixteen EIF2AK4 variants that had been identified in patients. By experimentally testing the functional integrity of the integrated stress response (ISR) downstream of GCN2, we determined that existing computational tools have insufficient sensitivity to reliably predict impaired kinase function. We determined experimentally that several EIF2AK4 variants identified in patients with classical PAH had preserved function and are therefore likely to be non-pathogenic. The dysfunctional variants of GCN2 that we identified could be subclassified into three groups: misfolded, kinase-dead, and hypomorphic. Intriguingly, members of the hypomorphic group were amenable to paradoxical activation by a type-1½ GCN2 kinase inhibitor. This experiment approach may aid in the clinical stratification of EIF2AK4 variants and potentially identify hypomorophic alleles receptive to pharmacological activation.

Retrospective analysis of dogs and cats with a mixed form of pulmonary hypertension and suspected pulmonary capillary hemangiomatosis in comparison to animals with predomination of precapillary pulmonary hypertension

Background: Pulmonary capillary hemangiomatosis (PCH) is an idiopathic disease with the anomalous proliferation of a small capillary-like vessel in the pulmonary tissue, which can lead to a severe form of PH. There are only several cases of PCH described in veterinary literature: 27 cases in dogs and 2 cases in cats. In veterinary medicine, PH is mostly recognized as a consequence of left heart failure as a progression of the postcapillary PH to the precapillary form. PCH is mostly described as a primary disease, but resistant postcapillary PH with the high possibility of pulmonary edema raises a speculation that PCH could be a secondary malformation to the left heart disease. Aim: Discover the features associated with the shift between left- and right-sided heart disease in the context of PH development Methods: Retrospective analysis of materials from cats and dogs with histological markers of PCH (sPCH) versus those with right heart failure (RHF). Results: Animals with histological and immunohistochemistry markers of PCH had previous history of disease with the left heart volume overload. There were no differences between the groups in radiography and gross pathology. Histologically, pulmonary fibrosis and arteriopathy could be found in RHF; in sPCH – a duplication of capillaries in alveolar septa and bizarre proliferation in surroundings structures. Conclusion: PCH could be a secondary pattern of vascular remodeling due to volume overload

A Rare Case of Pulmonary Veno-Occlusive Disease, Pulmonary Capillary Hemangiomatosis

A 40-year-old male with past medical history of chronic pain on methadone for a few years, hypertension, and obesity presented with worsening dyspnea and was found to have significant hypoxemia. A CT-angiogram of the chest showed extensive diffuse bilateral pulmonary infiltrates with bilateral hilar and mediastinal lymphadenopathy.

Pulmonary capillary hemangiomatosis: an unusual cause of primary pulmonary hypertension in pediatric age group

Pulmonary capillary hemangiomatosis (PCH) is a rare and controversial entity that is known to be a cause of pulmonary hypertension and is microscopically characterized by proliferation of dilated capillary-sized channels along and in the alveolar walls. Clinically, it is mostly seen in adults. PCH’s main clinical presentations are progressive dyspnea, fatigue, hemoptysis, palpitations and later irreversible pulmonary hypertension and right-sid­ed heart failure. It is characterized by severe hypoxemia, centrilobular ground-glass opacities on computed tomography and pulmonary congestion triggered by pulmonary vasodilating therapy. The imaging features include diffuse centrilobular ground‑glass opacities with features of pulmonary hypertension. We present a case of PCH in a 4‑year‑old boy who was diagnosed with post-partum hemorrhage (PPH) in echocardiography and computed tomography of the thorax.

Bilateral lung transplantation for pediatric pulmonary arterial hypertension: perioperative management and one-year follow-up.

Bilateral lung transplantation (LuTx) remains the only established treatment for children with end-stage pulmonary arterial hypertension (PAH). Although PAH is the second most common indication for LuTx, little is known about optimal perioperative management and midterm clinical outcomes. Prospective observational study on consecutive children with PAH who underwent LuTx with scheduled postoperative VA-ECMO support at Hannover Medical School from December 2013 to June 2020. Twelve patients with PAH underwent LuTx (mean age 11.9 years; age range 1.9-17.8). Underlying diagnoses included idiopathic (n = 4) or heritable PAH (n = 4), PAH associated with congenital heart disease (n = 2), pulmonary veno-occlusive disease (n = 1), and pulmonary capillary hemangiomatosis (n = 1). The mean waiting time was 58.5 days (range 1-220d). Three patients were bridged to LuTx on VA-ECMO. Intraoperative VA-ECMO/cardiopulmonary bypass was applied and VA-ECMO was continued postoperatively in all patients (mean ECMO-duration 185 h; range 73-363 h; early extubation). The median postoperative ventilation time was 28 h (range 17-145 h). Echocardiographic conventional and strain analysis showed that 12 months after LuTx, all patients had normal biventricular systolic function. All PAH patients are alive 2 years after LuTx (median follow-up 53 months, range 26-104 months). LuTx in children with end-stage PAH resulted in excellent midterm outcomes (100% survival 2 years post-LuTx). Postoperative VA-ECMO facilitates early extubation with rapid gain of allograft function and sustained biventricular reverse-remodeling and systolic function after RV pressure unloading and LV volume loading.

PULMONARY CAPILLARY HEMANGIOMATOSIS: A CONUNDRUM FOR EXPERTS

PULMONARY CAPILLARY HEMANGIOMATOSIS: A CONUNDRUM FOR EXPERTS

Efficacy and safety of oral pulmonary vasodilators in pulmonary veno-occlusive disease.

Pulmonary veno-occlusive disease (PVOD) or pulmonary capillary hemangiomatosis (PCH) is a rare subtype of pulmonary hypertension with dismal prognosis. Limited data are available on the efficacy and safety of orally administered pulmonary vasodilators for PVOD/PCH. Whether and how systemic sclerosis (SSc) affects the clinical outcomes of PVOD/PCH is also unknown. This study aimed to determine the clinical and hemodynamic efficacy and safety of oral pulmonary vasodilators for PVOD/PCH and clarify the possible effects of SSc on the clinical presentation of PVOD/PCH. We retrospectively analyzed the clinical data of 15 patients with PVOD/PCH treated with oral pulmonary vasodilators in our department since 2001. Six of them had SSc. Oral pulmonary vasodilators were administered either as single agents (n = 10) or in combination (n = 5). Treatment improved the functional class of five patients, and pulmonary arterial pressure and pulmonary vascular resistance decreased by 10 ± 12 mmHg and 36 ± 19%, respectively (p < 0.05 for both, n = 13), whereas pulmonary edema developed in three patients. The mean survival was 3.9 years, and the 1- and 3-year survival rates were 93% and 65%, respectively. The clinical presentation, including survival, was similar between patients with and without SSc. In our PVOD/PCH cohort, oral pulmonary vasodilators caused pulmonary edema in 20% of patients, but more than 80% of patients experienced significant pulmonary vasodilatory effects, and the overall prognosis was better than that previously reported. SSc does not adversely affect the clinical outcomes of PVOD/PCH.

Pulmonary Capillary Haemangiomatosis: A Rare Cause of Pulmonary Hypertension

Pulmonary capillary haemangiomatosis (PCH) is a rare disorder of unknown aetiology, characterised by proliferating capillaries that invade the pulmonary interstitium, alveolar septae and the pulmonary vasculature. It is often mis-diagnosed as primary pulmonary hypertension and pulmonary veno-occlusive disease. Pulmonary capillary haemangiomatosis is a locally aggressive benign vascular neoplasm of the lung. We report the case of a 19-year-old female who was referred to us in the early post-partum period with severe pulmonary artery hypertension, which was diagnosed as PCH by open lung biopsy.

Pulmonary Capillary Hemangiomatosis and Refractory Hypoxemia During PH Therapy

<h3>Introduction</h3> Pulmonary capillary hemangiomatosis (PCH), a rare cause of pulmonary hypertension (PH), presents clinically with right heart dysfunction and may be indistinguishable from typical pulmonary arterial hypertension. Vasodilator therapy exacerbates hypoxemia in PCH despite improvement in heart failure symptoms. Lung transplant is the only definitive therapy. We present the case of a patient succumbing to progressive hypoxemia on PH therapy during lung transplant evaluation. Autopsy revealed PCH. <h3>Case Report</h3> A 42-year-old female with PH due to undifferentiated connective tissue disease presented with acute respiratory distress. She was diagnosed 2 years prior and initially treated with macitentan, tadalafil and diuretics with clinical improvement; however, worsening shortness of breath and new finding of hypoxemia developed after 1 year. Imaging revealed faint patchy nodular opacities initially attributed to UCTD-associated pneumonitis. Steroids and mycophenolate failed to achieve radiographic improvement. Repeat right heart catheterization showed continued elevation in pulmonary artery pressure and stably reduced cardiac output. Subcutaneous infusion of Treprostinil was initiated 2 months prior to admission, which worsened hypoxemia. Clinical diagnosis of pulmonary veno-occlusive disease (PVOD) vs PCH was suspected and lung transplant evaluation initiated. On admission, patient presented with syncope and was found to have refractory hypoxemia despite high-flow oxygen supplementation. Cardiogenic shock and hypoxemic respiratory failure ensued, resulting in hepatic and renal failure, leading to cardiac arrest and unsuccessful resuscitation. Autopsy showed PCH. <h3>Summary</h3> Refractory hypoxemia during up-titration of vasodilator therapy for PH should prompt clinical suspicion for atypical causes of PH such as PCH. Early lung transplant referral is essential if PCH/PVOD is suspected given its poor prognosis and potentially harmful responses associated with traditional PH therapy.

Prospective clinical assessment of patients with pulmonary arterial hypertension switched from bosentan to macitentan (POTENT).

Even though pulmonary arterial hypertension (PAH) remains an incurable disease, the combination of PAH‐specific therapies allowed evolving from symptom‐based strategies to others aiming to move patients to low‐risk conditions. Endothelin‐1 (ET‐1) receptor antagonists emerged as specific‐PAH drugs that can be used in combination with other specific therapies. This work aimed to perform a prospective clinical assessment of patients with PAH that switched from bosentan to macitentan (POTENT), due to inadequate response. POTENT is a prospective, open‐label, single‐arm, uncontrolled study including PAH patients from our ongoing SAUDIPH registry. It enrolled 50 PAH patients divided as follows: idiopathic/heritable pulmonary arterial hypertension (I/HPAH); n = 24; PAH associated with congenital heart disease, n = 19; PAH associated with connective tissue diseases, n = 5; and pulmonary veno‐occlusive disease and/or pulmonary capillary haemangiomatosis (PVOD/PCH), n = 2. At baseline, most patients were in World Health Organization Functional Class (WHO FC) II/III (52.0%). After switching to macitentan, patients were more likely to be in WHO FC I/II (78%) and 22% of the overall cohort moved to a lower risk condition, with three low risk stratification parameters. Mean 6‐min walking distance increased about 34 m after 12 months, with a significant mean change over time (12.63 ± 11.69 at month 3 vs. 40.75 ± 12.57 at month 12, p = 0.002). Most haemodynamic parameters decreased over time, with corresponding negative mean changes (p < 0.001). The safety of macitentan was confirmed by the absence of anaemia and liver injury; clinical worsening was observed only in a small group of patients. In general, macitentan might be a valid alternative to bosentan in PAH stable patients on combination therapy with insufficient clinical response, and presenting intermediate and high‐risk parameters. We anticipate that studying this strategy in PAH subgroups would further clarify its potential and limitations.

Dual-energy CT lung perfusion characteristics in pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis (PVOD/PCH): preliminary experience in 63 patients.

In the stratification of potential causes of PH, current guidelines recommend performing V/Q lung scintigraphy to screen for CTEPH. The recognition of CTEPH is based on the identification of lung segments or sub-segments without perfusion but preserved ventilation. The presence of mismatched perfusion defects has also been described in a small proportion of idiopathic pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis (PVOD/PCH). Dual-energy CT lung perfusion changes have not been specifically investigated in these two entities. To compare dual-energy CT (DECT) perfusion characteristics in PAH and PVOD/PCH, with specific interest in PE-type perfusion defects. Sixty-three patients with idiopathic or heritable PAH (group A; n = 51) and PVOD/PCH (group B; n = 12) were investigated with DECT angiography with reconstruction of morphologic and perfusion images. The number of patients with abnormal perfusion did not differ between group A (35/51; 68.6%) and group B (6/12; 50%) (p = 0.31) nor did the mean number of segments with abnormal perfusion per patient (group A: 17.9 ± 4.9; group B: 18.3 ± 4.1; p = 0.91). The most frequent finding was the presence of patchy defects in group A (15/35; 42.9%) and a variable association of perfusion abnormalities in group B (4/6; 66.7%). The median percentage of segments with PE-type defects per patient was significantly higher in group B than in group A (p = 0.041). Two types of PE-type defects were depicted in 8 patients (group A: 5/51; 9.8%; group B: 3/12; 25%), superimposed on PH-related lung abnormalities (7/8) or normal lung (1/8). The iodine concentration was significantly lower in patients with abnormal perfusion (p < 0.001) but did not differ between groups. Perfusion abnormalities did not differ between the two groups at the exception of a higher median percentage of segments with PE-type defects in patients with PVOD/PCH. • Patchy perfusion defect was the most frequent pattern in PAH. • A variable association of perfusion abnormalities was seen in PVOD/PCH. • Lobular and PE-type perfusion defects larger than a sub-segment were depicted in both PAH and PVOD/PCH patients.

Guest Editor's Memo: Genetics Moves To Center Stage

Our understanding of pulmonary hypertension (PH) has advanced steadily. Almost 100 years ago, light microscopy provided the earliest insights into a rare progressive and fatal disease, primary pulmonary hypertension (“PPH”). Pathologists described the histopathology of PPH, with terms like “plexogenic” and “microthromboembolic” PPH. Pathologists, who specialized in pulmonary vascular disease, identified two rare disorders, pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH), that mimicked PPH clinically, but were distinctly different under the microscope.By the middle of the 20th century, the introduction of pulmonary artery catheterization to the study of cardiovascular diseases produced a new level of understanding of PH based upon physiologic observations of intravascular pressures and flows, with an emphasis on mechanisms that caused constriction and relaxation of pulmonary arterioles. This era supported early efforts to treat sporadic PPH and familial PPH, now known as idiopathic and heritable pulmonary arterial hypertension (PAH) with vasodilators, eventually leading to treatments which targeted three pathways integral to vasoconstriction and vasodilation of pulmonary arterioles.Even as pathologic, physiologic, and treatment studies proceeded during the second half of the 20th century, the genetic era began. Investigators took advantage of scientific advances in genetics to discover heritable causes of PH. The first breakthrough occurred in 2000, when two research teams independently reported that mutations in the gene (BMPR2), encoding the bone morphogenetic protein type 2 receptor, caused familial PPH. Over the next two decades investigators linked DNA sequence variations in 16 additional genes to heritable forms of PAH, including PVOD and PCH. These discoveries shaped a new understanding of PAH.Investigators quickly determined that BMPR2 regulated the proliferation of vascular cells, not vasoconstriction. Recognition of the pivotal role of cellular proliferation and transforming growth factor β (TGF-β) signaling paved the way for a new approach to the treatment of PAH. In the Study of Sotatercept for the Treatment of Pulmonary Arterial Hypertension (PULSAR), sotatercept, a fusion protein that impairs activation of a TGFβ pro-proliferative pathway, produced a greater reduction in pulmonary vascular resistance than placebo. Now studies are underway to assess the efficacy and safety of sotatercept across a broad spectrum of PAH disease severity.We have entered a new era of understanding and treating PAH, as genetics moves to center stage. This issue of Advances in Pulmonary Hypertension was organized to serve as a valuable resource for the PH community. The first article, authored by Drs. Carrie Welch and Wendy Chung of Columbia University, provides a comprehensive overview of the genomics of pulmonary hypertension. With this foundation in place, the second article, authored by Rachel Sullivan, MD (Stanford University) and Eric Austin, MD (Vanderbilt University) reviews the relationships between specific gene sequence variations and PAH phenotypes that clinicians are likely to encounter.In recent years genetic counseling and genetic testing have become important affordable services for patients with PAH and their families. Sumathi Rachamadugu, MSc, MS and Melanie Emmerson, MS (Intermountain Healthcare) collaborated with Barbara Girerd, PhD (Université Paris-Saclay) and Hunter Best, PhD (University of Utah) to provide an in depth introduction pretest genetic counseling, genetic testing, and posttest genetic counseling for PAH patients and their families. The PH Professional network contribution by Athena Angelopoulos, MS and Rachel Farrell, MS (University of California San Francisco) complements the preceding article by providing additional details related to genetic counseling and testing for PAH patients and their families.Finally, Drs. Austin, Chung, and Yu, joined us for a roundtable discussion on the genetics of pulmonary hypertension. Participants shared their personal knowledge of the history of genetic research and discovery related to PH, their advice on discussing genetic aspects of PH with patients and families, their thoughts about involving genetic counselors and ordering genetic tests, as well as how genetic test results influence treatment decisions and how knowledge of molecular pathways informs the development of new medications to treat PAH.In closing, we thank the authors and everyone at PHA and Allen Press who worked so hard to produce this issue of Advances.

Genetic Counseling and Testing for Pulmonary Arterial Hypertension in the United States

Genetic Counseling and Testing for Pulmonary Arterial Hypertension in the United States

PH Roundtable: Genetics and Pulmonary Hypertension

PH Roundtable: Genetics and Pulmonary Hypertension

Clinical case of a patient with pulmonary capillary hemangiomatosis: rapid progression or lost time?

The article describes a clinical case of a 37-year-old patient with pulmonary capillary hemangiomatosis of functional class IV according to the WHO classification with difficulties of diagnostic search and features of PAH-specific therapy.Pulmonary arterial hypertension - group 1 in the clinical classification is represented by several forms of pathology, including very rare diseases such as pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis.The difficulties of diagnostic search consist in the absence of specific symptoms, a variety of interstitial or focal changes according to spiral computed tomography, and the final diagnosis can be made only after performing a lung biopsy, which is associated with a high risk of possible complications. During the initial treatment and examination of the patient, clinical and hemodynamic parameters did not immediately allow to suspect the presence of pulmonary capillary hemangiomatosis. And only the difficulties of the patient’s management associated with the lack of the expected effect of the therapy with PAH-specific drugs served as the basis for further diagnostic search.Against the background of taking vasodilators, with the normalization of hemodynamic parameters, the progression of respiratory and right ventricular insufficiency was noted in the patient. According to the results of an additional examination, a diagnosis of pulmonary capillary hemangiomatosis was established, therapy was corrected and further tactics of management and treatment of the patient were determined. Currently, the patient is awaiting transplantation at V.I. Shumakov national medical research center and receives specific therapy with riociguate 2.5 mg TID and bosentan 125 mg BID.

Rapidly Progressive Respiratory Failure in Patient With Late Onset Pulmonary Capillary Hemangiomatosis.

Rapidly Progressive Respiratory Failure in Patient With Late Onset Pulmonary Capillary Hemangiomatosis.

PULMONARY CAPILLARY HEMANGIOMATOSIS: A RARE CASE OF STABLE DISEASE WITHOUT TREATMENT

SESSION TITLE: Medical Student/Resident Pulmonary Vascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Pulmonary capillary hemangiomatosis (PCH) is a rare cause of primary pulmonary hypertension caused by extensive proliferation of pulmonary capillaries within parenchymal, vascular, and bronchial tissue. Typically, PCH progresses rapidly with a median time to lung transplantation of two years post diagnosis. To our knowledge, we present the longest case of biopsy proven PCH that has been stable without treatment for seven years. CASE PRESENTATION: A healthy 23-year old non-smoking male presented to the emergency department (ED) with a 2-week history of hemoptysis associated with intermittent left-sided pleuritic chest pain, fatigue, and dyspnea. His physical exam, routine lab work, and chest X-ray were unremarkable. He was discharged home and prescribed clarithromycin for suspected bronchitis. He returned to the ED months later with ongoing symptoms and was referred for urgent outpatient consultation to pulmonology. Bronchoscopy was performed with no blood on bronchoalveolar lavage analysis. Further serum rheumatologic and vasculitis panels were negative. A non-contrast computed tomography (CT) scan of his chest revealed subtle bilateral upper lung predominant centrilobular ground-glass opacities. (Figure 1) With worsening hemoptysis, he returned to the ED six months later. A CT Chest angiogram was performed and showed progressive bilateral airspace opacities. (Figure 2) The patient was referred to Thoracic Surgery for lung biopsy. This demonstrated septal proliferation of capillaries consistent with PCH without evidence of vasculitis, venous occlusion or microorganisms. Immunofluorescence staining was also negative. (Figure 3) The patient remains stable with no signs of progression or pulmonary hypertension on echocardiogram. His enhanced CT and pulmonary function tests remain normal seven years from his initial presentation. DISCUSSION: The typical presentation of PCH includes progressive dyspnea, cough with or without hemoptysis, chest pain, and fatigue. (1) Chest X-ray can be normal or progress to demonstrate bilateral opacities in keeping with diffuse alveolar hemorrhage (DAH). CT chest often shows diffuse centrilobular ground-glass opacities. (1) Bronchoscopy may not reveal erythrocytes if the patient is not actively bleeding. Diagnosis of PCH is essential, as vasodilators used in pulmonary hypertension can cause hemodynamic instability in PCH. (2) Interestingly, an autopsy case series found incidental cases of PCH in patients who were asymptomatic during life. (3) This raises the possibility that subclinical cases of PCH may exist which do not require urgent referral for lung transplantation. CONCLUSIONS: This case represents the longest active case of PCH after confirmation with biopsy without treatment. Re-evaluating the expected prognosis for individuals diagnosed with PCH is important, as median survival may be longer than currently reported in the literature. Reference #1: O'keefe MC, and Post MD. Pulmonary Capillary Hemangiomatosis: A Rare Cause of Pulmonary Hypertension. Archives of Pathology & Laboratory Medicine, 2015;139(2):274–277. Reference #2: Almagro P, Julia J, Sanjuame M, Gonalez G, Casalots J, Heredia JL, et al. Pulmonary Capillary Hemangiomatosis Associated with Primary Pulmonary Hypertension. Medicine. 2002;81(6):417–24. Reference #3: Havlik DM, Massey LW, Williams WL, and Crooks LA. Pulmonary Capillary Hemangiomatosis- like foci: an autopsy study of 8 cases. Anatomic Pathology. 2000;113(5):665-662. DISCLOSURES: No relevant relationships by Meredith Chiasson, source=Web Response No relevant relationships by Jasper Johar, source=Web Response No relevant relationships by Daria Manos, source=Web Response No relevant relationships by Matthew Nunn, source=Web Response

Autopsy study of pulmonary capillary hemangiomatosis with inflammatory cell infiltration into the myocardium

Pulmonary capillary hemangiomatosis is a rare form of pulmonary artery hypertension; to date, only few descriptions of myocardial pathology in pulmonary capillary hemangiomatosis have been reported in the literature. We report the case of a Japanese female patient who was diagnosed with pulmonary capillary hemangiomatosis combined with acute myocardial inflammation on performing autopsy. She was admitted to our hospital because of acute pneumonia and subsequently suddenly developed severe hypoxemia with breathing difficulty and died 13 days after admission. At autopsy, the histology of the lung was consistent with pulmonary capillary hemangiomatosis. Additionally, a diffuse severe infiltration of inflammatory cells was associated with edema in the myocardium. Myocytolysis was limited and fibrosis was absent. To the best of our knowledge, pulmonary capillary hemangiomatosis with acute myocarditis-like histological findings has been described for the first time through our case.

Computed tomography appearances of the lung parenchyma in pulmonary hypertension.

Computed tomography (CT) is a valuable tool in the workup of patients under investigation for pulmonary hypertension (PH) and may be the first test to suggest the diagnosis. CT parenchymal lung changes can help to differentiate the aetiology of PH. CT can demonstrate interstitial lung disease, emphysema associated with chronic obstructive pulmonary disease, features of left heart failure (including interstitial oedema), and changes secondary to miscellaneous conditions such as sarcoidosis. CT also demonstrates parenchymal changes secondary to chronic thromboembolic disease and venous diseases such as pulmonary venous occlusive disease (PVOD) and pulmonary capillary haemangiomatosis (PCH). It is important for the radiologist to be aware of the various manifestations of PH in the lung, to help facilitate an accurate and timely diagnosis. This pictorial review illustrates the parenchymal lung changes that can be seen in the various conditions causing PH.

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.