Connective tissue disease-related interstitial lung disease (CTD-ILD) and interstitial lung abnormality (ILA): Evolving concept of CT findings, pathology and management.

Connective tissue diseases (CTDs) demonstrating features of interstitial lung disease (ILD) include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), dermatomyositis (DM) and polymyositis (PM), ankylosing spondylitis (AS), Sjogren syndrome (SS), and mixed connective tissue disease (MCTD). On histopathology of lung biopsy in CTD-related ILDs (CTD-ILDs), multi-compartment involvement is an important clue, and when present, should bring CTD to the top of the list of etiologic differential diagnoses. Diverse histologic patterns including nonspecific interstitial pneumonia (NSIP), usual interstitial pneumonia (UIP), organizing pneumonia, apical fibrosis, diffuse alveolar damage, and lymphoid interstitial pneumonia can be seen on histology in patients with CTD-ILDs. Although proportions of ILDs vary, the NSIP pattern accounts for a large proportion, especially in SSc, DM and/or PM and MCTD, followed by the UIP pattern. In RA patients, interstitial lung abnormality (ILA) is reported to occur in approximately 20-60% of individuals of which 35-45% will have progression of the CT abnormality. Subpleural distribution and greater baseline ILA involvement are risk factors associated with disease progression. Asymptomatic CTD-ILDs or ILA patients with normal lung function and without evidence of disease progression can be followed without treatment. Immunosuppressive or antifibrotic agents for symptomatic and/or fibrosing CTD-ILDs can be used in patients who require treatment.

Interstitial lung abnormality (ILA) and nonspecific interstitial pneumonia (NSIP).

This review article aims to address mysteries existing between Interstitial Lung Abnormality (ILA) and Nonspecific Interstitial Pneumonia (NSIP). The concept and definition of ILA are based upon CT scans from multiple large-scale cohort studies, whereas the concept and definition of NSIP originally derived from pathology with evolution to multi-disciplinary diagnosis. NSIP is the diagnosis as Interstitial Lung Disease (ILD) with clinical significance, whereas only a part of subjects with ILA have clinically significant ILD. Eventually, both ILA and NSIP must be understood in the context of chronic fibrosing ILD and progressive ILD, which remains to be further investigated.

Connective tissue disease-related interstitial lung disease (CTD-ILD) and interstitial lung abnormality (ILA): Evolving concept of CT findings, pathology and management.

The connective tissue diseases (CTDs) demonstrating features of interstitial lung disease (ILD) include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), progressive systemic sclerosis (PSS), dermatomyositis (DM) and polymyositis (PM), ankylosing spondylitis (AS), Sjogren's syndrome (SS), and mixed connective tissue disease (MCTD). In RA patients in particular, interstitial lung abnormality (ILA) (of varying degrees; severe vs. mild) is reported to occur in approximately 20-60 % of individuals and CT disease progression occurs in approximately 35-45 % of them. The ILAs have been associated with a spectrum of functional and physiologic decrement. The identification of progressive ILA may enable appropriate surveillance and the commencement of treatment with the goal of improving morbidity and mortality rates of established RA-ILD. Subpleural distribution and higher baseline ILA/ILD extent were risk factors associated with disease progression. At histopathologic analysis, connective tissue disease-related interstitial lung diseases (CTD-ILDs) are diverse and include nonspecific interstitial pneumonia (NSIP), usual interstitial pneumonia (UIP), organizing pneumonia (OP), apical fibrosis, diffuse alveolar damage (DAD), and lymphoid interstitial pneumonia (LIP). Even though proportions of ILDs vary, NSIP pattern accounts for a large proportion, especially in PSS, DM/PM and MCTD, followed by UIP pattern. Evidence has been published that treatment of subclinical CT lung abnormalities showing a tendency to progress to ILD may stabilize the CT alterations. The identification of subclinical lung abnormalities can be appropriate in the management of the disease and CT appears to be the gold standard for the evaluation of lung parenchyma.

IgG4-related disease presenting with combined pulmonary fibrosis and emphysema (CPFE).

A 64-year-old man was admitted to our hospital with an abnormal chest shadow. The patient was a current-smoker and had a past illness of autoimmune pancreatitis with a high serum level of IgG4, 348 mg/dL. Chest CT showed upper-lobe emphysema, and lower-lobe reticulation with honeycombing, suggestive of combined pulmonary fibrosis with emphysema (CPFE). Surgical lung biopsy was revealed a usual interstitial pneumonia pattern with marked infiltration of IgG4-positive plasma cells. The patient was diagnosed with IgG4 related disease (IgG4-RD) presenting with CPFE. Pulmonary manifestation was improved by corticosteroid therapy. IgG4-RD may be an underlying condition in patient with CPFE.