Association between preexisting lung involvements and the risk of diffuse alveolar hemorrhage in patients with microscopic polyangiitis: A multi-center retrospective cohort study

Latent class analysis of chest CT abnormalities to define subphenotypes in patients with MPO-ANCA-positive microscopic polyangiitis

BACKGROUND

Patients with microscopic polyangiitis (MPA) and positive myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) may present with various abnormalities in chest computed tomography (CT). This study aimed to identify subphenotypes using latent class analysis (LCA) and to explore the relationship between the subphenotypes and clinical patterns, as well as compare the clinical characteristics of these subphenotypes in patients with MPO-ANCA-positive MPA (MPO-MPA).

METHODS

The study identified subphenotypes using LCA based on chest CT findings in 178 patients with MPO-MPA and pulmonary involvement from June 2014 to August 2022.

RESULTS

LCA identified 27 participants (15.2%) in class 1, 43 (24.1%) in class 2, 35 (19.7%) in class 3, and 73 (41.0%) in class 4. Class 1 was characterized by prominent inflammatory exudation, class 2 by fibrosis and architectural distortion, class 3 by predominantly bronchiectasis, and class 4 by lesions mixed with inflammation and fibrosis. Class 1 had the highest level of extrapulmonary disease activity, with 77.8% of patients experiencing diffuse alveolar hemorrhage. Class 2 had the lowest level of extrapulmonary disease activity, with 41.9% of patients showing usual interstitial pneumonia. Class 3 patients were more likely to have complications involving the ear, nose, and throat, as well as pulmonary infections before treatment, and they exhibited the best outcomes. The characteristics and outcomes of class 4 were intermediate among the four classes.

CONCLUSIONS

These findings suggest that bronchiectasis may represent a unique pattern of pulmonary involvement in MPO-MPA, highlighting the importance of screening for bronchiectasis in MPO-MPA and identifying optimal management strategies.

Bronchiectasis in patients with antineutrophil cytoplasmic antibody-associated vasculitis: a case control study on clinical features and prognosis

BACKGROUND

Bronchiectasis was reported in 2%-40% of patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV), but there were no studies on the prevalence, risk factors and impact of AAV-associated bronchiectasis in Chinese patients.

RESEARCH DESIGN AND METHODS

AAV patients were retrospectively enrolled. The clinical, laboratory and imaging features and the prognosis were analyzed and compared between those with and without bronchiectasis.

RESULTS

Bronchiectasis was present in 48/212 (22.6%) of our AAV patients, among whom 41 were confirmed in 210 patients (19.5%) who received chest HRCT at the initial diagnosis of AAV. There were more women and fewer smokers in those with bronchiectasis as compared to those without. Cases with positive anti-MPO were more likely to have bronchiectasis (26.2%), and those with bronchiectasis were more likely to be anti-MPO positive (93.8%). Patients who had a diagnosis of bronchiectasis before AAV were more likely to have nervous system involvement, while patients without bronchiectasis had higher 24h proteinuria. The presence of bronchiectasis showed no significant effect on the 1, 3, 5-year survival.

CONCLUSIONS

Nearly 20% of patients showed bronchiectasis on chest HRCT at the initial diagnosis of AAV, and positivity of anti-MPO was associated with bronchiectasis in a Chinese cohort of AAV patients.

Clinical Significance of Interstitial Lung Disease and Its Acute Exacerbation in Microscopic Polyangiitis

BACKGROUND

Presence of interstitial lung disease (ILD) is thought to be associated with mortality in microscopic polyangiitis (MPA); however, evidence on MPA-ILD remains lacking. Acute exacerbation (AE) refers to rapidly progressive, fatal respiratory deterioration that may develop in patients with various ILDs. No study has investigated the clinical significance of AE in MPA-ILD.

RESEARCH QUESTION

We aimed to determine the clinical picture and prognostic factors, the incidence of AE, and the risk factors in patients with MPA-ILD.

STUDY DESIGN AND METHODS

Eighty-four consecutive patients with MPA-ILD and 95 patients with MPA-non-ILD were analyzed. We also compared 80 patients with MPA-ILD and 80 patients with idiopathic interstitial pneumonia without myeloperoxidase-antineutrophil cytoplasmic antibody positivity (ILD alone), who were matched for age, sex, and chest high-resolution CT scan pattern.

RESULTS

The MPA-ILD group had a higher frequency of men and smokers and was associated with higher mortality than the MPA-non-ILD group. The matched MPA-ILD group had a higher mortality rate than the matched ILD alone group. There was no significant difference in AE incidence between the matched MPA-ILD and ILD alone groups (1-year AE cumulative incidence rate, 7.5% and 5.2%, respectively; P = .75). In the MPA-ILD group, a lower percent predicted FVC (%FVC) was independently associated with a higher mortality rate (hazard ratio [HR], 0.96 per 1% increase; P < .01) and a higher AE incidence rate (HR, 0.96 per 1% increase; P = .01). On multivariable Cox regression analysis with time-dependent covariates, developing AE during their clinical course was strongly associated with shorter survival (HR, 17.1; P < .001).

INTERPRETATION

MPA-ILD represented a distinct phenotype with poor prognosis. Lower %FVC was an independent prognostic factor. Patients with lower %FVC had a risk of developing AE, which was a strong prognostic determinant. The specific management for MPA-ILD and AE should be established.

Cobalamin C deficiency presenting with diffuse alveolar hemorrhage and pulmonary microangiopathy

OBJECTIVE

Combined methylmalonic acidemia and homocysteinemia is a genetically heterogeneous disorder of cobalamin (cbl; vitamin B12) metabolism, which consists of five subtypes including cblC, cblD, cblF, cblJ, and cblX deficiencies. The purpose of this study is to summarize new clinical features mainly diffuse alveolar hemorrhage (DAH) in cblC deficiency.

METHODS

We made a retrospective analysis of four pediatric patients diagnosed with DAH and pulmonary microangiopathy due to cblC deficiency between January 2017 and December 2018 in Beijing Children's Hospital.

RESULTS

This study describes four patients with their ages ranging from 4 years 2 months to 7 years 6 months with cblC deficiency who developed late-onset diffuse lung disease (DLD). Of these, the first three patients presented predominantly with DAH, and the last patient with pulmonary microangiopathy confirmed by thoracoscopic lung biopsy. All patients were accompanied by pulmonary arterial hypertension (PAH), two accompanied by respiratory failure, and two accompanied by moderate megaloblastic anemia. Diffuse ground-glass opacification and poorly defined ground-glass centrilobular nodules were seen on high-resolution computed tomography in one patient and three patients, respectively. All patients were suspected of having idiopathic pulmonary hemosiderosis or interstitial lung disease at other hospitals. All of them received treatment with corticosteroid before admission, but the symptoms did not improve. Moreover, all patients carried compound heterozygous mutations (c.80A>G, c.609G>A) in MMACHC and improved significantly after being treated for cblC deficiency and PAH.

CONCLUSIONS

CblC deficiency should be considered in the differential diagnosis of DAH especially with PAH, and pulmonary microangiopathy be the main reason of DLD in these patients.