Interstitial Lung Diseases Flashcards
Interstitial lung disease: clinical
Dyspnea, noticed initially on exertion
Nonproductive cough
Crackles prominent at lung bases
Clubbing may be present
Interstitial lung disease: patho
Decreased compliance (increased stiffness) of lungs
Decreased lung volumes
Loss of alveolar-capillary surface area resulting in impaired measured diffusion
Abnormalities in small airway function without generalized airflow obstruction
Hypoxemia without CO2 retention
Pulmonary hypertension
Interstitial lung disease: CXR
Reticular – increased linear markings
Reticulonodular – increased linear and small nodular markings
10% have normal radiographic findings
High-resolution computed tomography (HRCT)
Can distinguish inflammation from fibrosis
Picks up early changes
Specific pattern may be suggestive of a particular diagnosis
Idiopathic Interstitial Pneumonias
Usual interstitial pneumonia Desquamative interstitial pneumonia Respiratory bronchiolitis interstitial lung disease Nonspecific interstitial pneumonia Acute interstitial pneumonia Cryptogenic organizing pneumonia Lymphocytic interstitial pneumonia
Usual interstitial pneumonia
Patchy areas of parenchymal fibrosis and interstitial inflammation interspersed between areas of relatively preserved lung tissue
Fibrosis is the most prominent component of the pathology
Honeycombing – cystic airspace from retraction of surrounding fibrotic tissue
Most important disorder in this category is idiopathic pulmonary fibrosis
Desquamative interstitial pneumonia
More homogenous than UIP
Large number of intraalveolar mononuclear cells
Less prominent inflammation and little associated fibrosis
Uniform process
Minimal architectural distortion
Pigmented macrophages in respiratory bronchioles secondary to smoking
Smoking is believed to be an important underlying cause
Respiratory bronchiolitis interstitial lung disease
Related to DIP
Associated with pigmented macrophages which are present within the lumen of respiratory bronchioles
Interstitial inflammation is not present
Almost always associated with smoking
Most important intervention is smoking cessation
Nonspecific interstitial pneumonia
Mononuculear cell infiltration within the alveolar walls Uniform process Fibrosis is variable, but less than UIP Idiopathic or connective tissue disorder Better prognosis
Acute interstitial pneumonia
Organizing or fibrotic stage of alveolar damage, which is the histologic pattern seen in ARDS.
No initial trigger identified.
Histology shows fibroblast proliferation and type II pneumocyte hyperplasia in the setting of what appears to be organizing alveolar damage
Cryptogenic organizing pneumonia
Organizing fibrosis (granulation tissue) in small airways
Mild degree of chronic interstitial inflammation
Intraluminal airway involvement is a key feature
Idiopathic
Differential: infections, toxic inhalants, or connective tissue disease
Idiopathic pulmonary fibrosis
No recognizable inciting agent Dysregulated pattern of fibrosis in response to alveolar epithelial injury Presents between ages 50-70 Insidious onset Dyspnea is the most common complaint Rales on lung examination Patients frequently have clubbing
Idiopathic pulmonary fibrosis: PE
Chest x-ray
Interstitial pattern that is generally bilateral and relatively diffuse
More prominent at lung bases, particularly in the peripheral subpleural regions
High Resolution CT
Interstitial densities that are patchy, peripheral, subpleural, and associated with small cystic spaces.
Honeycombing – indicated irreversible fibrosis
Idiopathic pulmonary fibrosis: diagnosis & progonosis
Diagnosis made with surgical lung biopsy
HRCT with classic pattern of honeycombing – diagnostic in patient too frail for lung biopsy
Prognosis
Poor with mean survival at time of diagnosis 2-5 years
No proven effective treatment
Desquamative interstitial pneumonia
Smokers
Subacute
Ground glass appearance on imaging
Lung biopsy with a uniform accumulation of intraalveolar macrophages with little or no fibrosis
Prognosis better than IPF
Improves with smoking cessation and may respond to corticosteroids
Nonspecific interstitial pneumonia
Ground glass appearance on imaging – inflammation
Lung biopsy with predominantly inflammatory response in the alveolar walls , with little fibrosis
Prognosis depends on degree of fibrosis
Patients often respond to corticosteroids
Cryptogenic organizing pneumonia
Connective tissue plug in small airway accompanied by mononuclear cell infiltration of the surrounding lung parenchyma
Large majority have no specific cause
Chest x-ray often mimics pneumonia with one or more alveolar infiltrates
Subacute presentation over weeks to months with constitutional as well as respiratory symptoms
Response to steroid is dramatic and occurs over days to weeks.
Therapy is usually prolonged for months to prevent relapse
Acute Interstitial Pneumonia
Acute disease that begins with the clinical picture of ARDS but without any usual inciting causes
Imaging with ground glass appearance, alveolar filling
Histology of diffuse alveolar damage, often showing some organization and fibrosis
Mortality is high
Small percentage of patients do well with clinical resolution and no long term sequelae
Rheumatoid Arthritis
Primary manifestation is inflammatory joint disease
Most common site of thorax involvement is the pleura
Pleurisy, pleural effusions or both
Lung parenchymal involvement includes one or multiple nodules or the development of interstitial lung disease
Interstitial lung disease is usually mild, but can be severe in some cases
Systemic lupus erythematosus
Multisystem disease that affects joints and skin
Serious organ involvement includes kidneys, lungs, nervous system, and heart
Involvement of the thorax includes pleural disease presenting with pleuritic chest pain, pleural effusion, or both
Acute pneumonitis in which infiltrates often involve the alveolar spaces as well as the alveolar walls
Less frequently chronic interstitial lung disease – extensive fibrosis usually not prominent
Progressive systemic sclerosis ( scleroderma)
Most obvious manifestation involve the skin and small blood vessels
Other organ system involvement include GI tract, lungs, kidneys, and heart
Pulmonary involvement tends to be severe with significant scarring of the pulmonary parenchyma
Pulmonary fibrosis strongly associated with an autoantibody to topoisomerase I (antitopoisomerase I, also called Scl70)
Pulmonary Artery Hypertension – small pulmonary vessel disease independent of the fibrosis
Polymyositis-dermatomyositis
Muscles and skin are the primary sites of the inflammatory process
Interstitial lung disease is relatively infrequent
Respiratory difficulty secondary to weakness of the diaphragm
Involvement of the striated muscles in the proximal esophagus may lead to dysphagia and recurrent aspiration pneumonia
Pulmonary Langerhans Histiocytosis
Also called eosinophilic granuloma of the lung or pulmonary histiocytosis X
Differential diagnosis of unexplained interstitial disease in the young or middle aged adult
Histiocytic cell appears to be an antigen-presenting dendritic or phagocytic cell called a Langerhans cell
Cytoplasmic rod like structures called X bodies (Burbeck Granules) which can be seen by electron microscopy
Light microscopy reveals histiocytes, eosinophils, lymphocytes, macrophages, and plasma cells
