The majority of connective tissue diseases (CTDs) are multisystem disorders that are often heterogeneous in their presentation and do not have a single laboratory, histologic, or radiologic feature that is defined as the gold standard to support a specific diagnosis. Given this challenging situation, the diagnosis of CTD is a process that requires the synthesis of multidisciplinary data which may include patient clinical symptoms, serologic evaluation, laboratory testing, and imaging. Pulmonary manifestations of connective tissue disease include interstitial lung disease as well as multicompartmental manifestations. These CT imaging patterns and features of specific diseases will be discussed in this article.

A 46-year-old male was treated with corticosteroids for nonspecific interstitial pneumonia (NSIP). He was referred to our hospital and admitted for worsening dyspnea and diffuse ground-glass opacity on chest computed tomography (CT) during corticosteroid treatment. Gottron\'s sign was observed, and the patient was diagnosed with clinically amyopathic dermatomyositis on skin biopsy. We increased the corticosteroid dose and added immunosuppressive agents; however, the opacity on the chest CT worsened. Based on periodic-acid-Schiff-positive granular material in the bronchoalveolar lavage fluid and the presence of anti-GM-CSF antibodies, the patient was diagnosed with autoimmune pulmonary alveolar proteinosis (APAP). The concentration of anti-GM-CSF antibodies in preserved serum was also elevated when the patient was diagnosed with NSIP. Thus, we assumed that NSIP and APAP coexisted, and that APAP manifested during immunosuppressive therapy. When exacerbation is observed during the treatment of interstitial pneumonia with immunosuppressive agents, it is necessary to consider APAP.

Interstitial lung diseases (ILDs) refer to a heterogeneous and complex group of conditions characterized by inflammation, fibrosis, or both, in the interstitium of the lungs. This results in impaired gas exchange, leading to a worsening of respiratory symptoms and a decline in lung function. While the etiology of some ILDs is unclear, most cases can be traced back to factors such as genetic predispositions, environmental exposures (including allergens, toxins, and air pollution), underlying autoimmune diseases, or the use of certain medications. There has been an increase in research and evidence aimed at identifying etiology, understanding epidemiology, improving clinical diagnosis, and developing both pharmacological and non-pharmacological treatments. This review provides a comprehensive overview of the current state of knowledge in the field of interstitial lung diseases.

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist\'s aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

BACKGROUND: Patients with idiopathic interstitial pneumonia (IIP) have a favourable prognosis when they have interstitial pneumonia with autoimmune features (IPAF). However, precise IPAF-related findings from high-resolution computed tomography (HRCT) and lung histopathological specimens and the treatment response have not been fully determined. Therefore, this study was conducted to evaluate the relationship between findings on HRCT or lung histopathological specimens and the progression of interstitial pneumonia in patients with IPAF.
METHODS: This multicentre cohort study prospectively enrolled consecutive patients with IIP. At the diagnosis of IIP, we systematically evaluated 74 features suggestive of connective tissue diseases and followed them up. HRCT, lung specimens, serum antibodies, and the clinical course were also evaluated.
RESULTS: Among 222 patients with IIP, 26 (11.7%) fulfilled the IPAF criteria. During a median observation period of 36 months, patients with IPAF showed better survival than those without IPAF (p = 0.034). While histopathological findings were not related to IPAF, nonspecific interstitial pneumonia (NSIP) with organizing pneumonia (OP) overlap was the most prevalent HRCT pattern (p < 0.001) and the consolidation opacity was the most common radiological finding in IPAF (p = 0.017). Furthermore, in patients with IPAF, the diagnosis of COP or NSIP with OP overlap was associated with a higher increase in %FVC in 1 year than in those with idiopathic pulmonary fibrosis, NSIP, or unclassifiable IIP (p = 0.002).
CONCLUSIONS: This study shows the presence of consolidation opacity on HRCT and the diagnosis of COP or NSIP with OP overlap are associated with IPAF and its favourable treatment response in patients with IPAF.

Differentiating between idiopathic interstitial pneumonia (IIP) and secondary interstitial pneumonia, particularly connective tissue disease-associated interstitial lung disease (CTD-ILD), can be challenging histopathologically, and there may be discrepancies among pathologists. While surgical lung biopsy has traditionally been considered the gold standard for diagnosing interstitial pneumonia, the usefulness of transbronchial lung cryobiopsy (TBLC) has been reported. If TBLC could effectively distinguish between primary and secondary diseases, it would provide a less invasive option for patients. The aim of this study was to identify specific pathologic findings in TBLC specimens that could assist in distinguishing CTD-ILD from IIP. A total of 93 underwent TBLC at Tenri Hospital between 2018 and 2022. We retrospectively reviewed cases of CTD-ILD exhibiting a nonspecific interstitial pneumonia (NSIP) pattern (CTD-NSIP) and cases of NSIP with an unknown etiology (NSIP-UE), as determined through multidisciplinary discussion. Nineteen patients with CTD-NSIP and 26 patients with NSIP-UE were included in the study for clinicopathological analysis. The CTD-NSIP group had a significantly higher proportion of female patients compared to the NSIP-UE group (79% vs. 31%; p = 0.002). The presence of both fresh and old intraluminal fibrosis within the same TBLC specimen was significantly more frequent in CTD-NSIP group than in the NSIP-UE group (p = 0.023). The presence of an NSIP pattern with co-existing fresh and old intraluminal fibrosis in TBLC specimens raised suspicion for CTD-ILD.

Interstitial lung disease and airway disease (AD) are often complicated with rheumatoid arthritis (RA) and have a poor prognosis. Several studies reported genetic associations with interstitial lung disease in RA. However, few genetic studies have examined the susceptibility to AD in RA patients. Here, we investigated whether single nucleotide variants susceptible to idiopathic pulmonary fibrosis might be associated with interstitial lung disease or AD in Japanese RA patients. Genotyping of rs2736100 [C/A] in TERT and rs1278769 [G/A] in ATP11A was conducted in 98 RA patients with usual interstitial pneumonia, 120 with nonspecific interstitial pneumonia (NSIP), 227 with AD, and 422 without chronic lung disease using TaqMan assays. An association with AD in RA was found for rs2736100 (p = 0.0043, Pc = 0.0129, odds ratio [OR] 1.40, 95% confidence interval [CI] 1.11-1.77). ATP11A rs1278769 was significantly associated with NSIP in older RA patients (>65 years, p = 0.0010, OR 2.15, 95% CI 1.35-3.40). This study first reported an association of rs2736100 with AD in RA patients and ATP11A rs1278769 with NSIP in older RA patients.

The anti-MDA5-associated autoimmune disease represents a poorly understood entity. The study\'s objectives were to describe a cohort of interstitial lung disease (ILD) patients who were positive for anti-MDA5 autoantibody and identify clinical risk factors associated with survival.
This single-center cohort study included ILD patients positive for anti-MDA5 autoantibody. Baseline clinical features were registered, and survival analysis was performed to identify risk factors associated with worse survival.
Fifty-three ILD-MDA5 positive patients were included; twelve died during follow-up due to rapidly progressive interstitial lung disease (RP-ILD). Dermatological signs of anti-MDA5 (Gottron papules, Gottron sign, palmar papules, V-neck sign, facial dermatomyositis rashes, and skin ulcers) were strongly associated with death secondary to RP-ILD (HR: 3.7, 95% CI: 1.02-13.35). Patients with dermatological signs were younger, had higher anti-MDA5 autoantibodies titers, more frequent inflammatory patterns in HRCT evaluation, and less fibrosis extent in HRCT.
Dermatological manifestation in ILD patients to anti-MDA5 autoantibodies are associated with RP-ILD and short-term fatal outcomes. Dermatological signs may identify a subgroup of ILD-positive to anti-MDA5 patients with a high risk of RP-ILD.

A 69-year-old Japanese man with acute leukemia received post-transplant cyclophosphamide-based haploidentical stem cell transplantation (PTCY-haplo-SCT) but was readmitted with dyspnea and ground-glass-opacities of the lungs. Bronchoscopy showed inflammatory changes with no signs of infection. He received steroids but required intubation as his condition deteriorated. In addition to antithymocyte globulin and cyclophosphamide, we administered ruxolitinib but failed to save him. Autopsy findings revealed fibrotic nonspecific interstitial pneumonia (NSIP) without evidence of organizing pneumonia or infection. Thus, we diagnosed idiopathic pneumonia syndrome (IPS). As far as our knowledge, this is the first case of IPS with NSIP histology after PTCY-haplo-SCT.

BACKGROUND: interstitial lung involvement occurs in 80% of chest CT scans of patients with systemic sclerosis (SS) and has a great impact on morbidity and mortality. The aim of the study was to describe factors associated with the development of interstitial lung disease (ILD) in patients diagnosed with SS in our division.
METHODS: a retrospective case-control study of patients followed up between 2005-2021 who met the classification criteria for SS was performed. ILD was defined as the finding of interstitial manifestations on high-resolution chest tomography (HRCT): non-specific interstitial pneumonia pattern (NSIP) or usual interstitial pneumonia (UIP), and/or findings on pulmonary function tests (FVC less than 80% and DLCO less than 80%). Patients with ILD (cases) and without it (controls) were identified. Demographic, clinical and serological variables were analyzed. Percentage, mean (SD) and median (IQR) measurements were calculated for each variable. A univariate and multivariate analysis was performed using logistic regression to establish its association with ILD.
RESULTS: Seventy nine patients with SS were included, 31 with ILD. Univariate analysis showed that sclerosis subtype (according to Le Roy classification), lung function measures, and anticentromere antibody positivity were factors associated with ILD in a statistically significant way. In the multivariate analysis, only the presence of anti-centromere antibodies was statistically significant.
CONCLUSIONS: the analysis of risk factors to determine the development and progression of lung damage is of vital importance for an early implementation of treatment, which would impact the mortality rate of patients with SS.
Introducción: el compromiso pulmonar intersticial se presenta en 80% de las tomografías de tórax de pacientes con esclerosis sistémica (ES) y tiene gran impacto en la morbimortalidad. El objetivo de este trabajo fue describir factores asociados al desarrollo de enfermedad pulmonar intersticial (EPI) en pacientes con diagnóstico de ES de nuestra división. Métodos: Se realizó un estudio retrospectivo, casos y controles, de pacientes seguidos entre 2005-2021 que cumplían criterios de ES. Se definió EPI al hallazgo de manifestaciones intersticiales en tomografía de tórax con cortes de alta resolución (TACAR): patrón neumonía intersticial no específica (NINE) o neumonía intersticial usual (NIU), y/o hallazgos en pruebas de función pulmonar (CVF menor al 80% y DLCO menor al 80%). Se identificaron pacientes con EPI (casos) y sin ella (controles). Se analizaron variables demográficas, clínicas y serológicas. Se calcularon medidas de porcentaje, media (DS) y mediana (RIQ) en cada variable. Se efectuó análisis univariado y multivariado, mediante regresión logística para establecer su asociación con EPI. Resultados: Se incluyeron 79 pacientes con ES, 31 con EPI. El análisis univariado demostró que el subtipo de esclerosis (según clasific ación Le Roy), las medidas de función pulmonar y positividad del anticuerpo anticentrómero fueron factores asociados en forma estadísticamente significativa con EPI. En el análisis multivariado solo la presencia de anticuerpos anti-centrómero fue estadísticamente significativa. Discusión: el análisis de los factores de riesgo para determinar desarrollo y progresión de daño pulmonar tiene vital importancia para una implementación temprana del tratamiento, lo que impactaría en la tasa de mortalidad de los pacientes con ES.