Interstitial Lung Disease Flashcards
Interstitial Lung Disease
- Large group of disorders that affect the alveolar wall that ultimately lead to diffuse scarring or fibrosis
- Misnomer: Interstitial lung disease affects all components of the alveolar wall which include epithelial cells, endothelial cells, and the interstitium
Interstitial lung disease
Clinical Manifestations
- Clinical Manifestations
- Dyspnea, noticed initially on exertion
- Nonproductive cough
- Crackles prominent at lung bases
- Clubbing may be present
Interstitial lung disease
Pathophysiology
- Pathophysiology
- 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
Imaging
- Chest x-ray
- 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
Interstitial lung disease
Testing
- Tissue specimens for diagnosis
- Thorascopic lung biopsy
- Transbronchial biopsy via flexible bronchoscopy
- Bronchoalveolar lavage
- PFT
- Restrictive pattern
- Decreased lung volumes
- hypoxia
Interstitial Lung Disease
Classification
- Classification
- Known Etiology ~ 35%
- Inhaled inorganic dusts (pneumoconiosis such as asbestosis or silicosis)
- Organic antigens ( hypersensitivity pneumonitis)
- Known Etiology ~ 35%
- Unknown Etiology ~65%
- Idiopathic interstitial pneumonias
- Connective tissue diseases (rheumatic disease)
- Sarcoidosis
Interstitial Lung Disease
Unknown Etiology – continued
- Unknown Etiology – continued
- Less Common
- Pulmonary Langerhans cell histiocytosis
- Lymphangioleiomyomatosis
- Goodpasture’s Syndrome
- Wegener’s granulmomatosis
- Chronic eosinophilic pneumonia
- Pulmonary alveolar proteinosis
- Less Common
Interstitial Lung Disease
Pathologic Process
- Pathologic Processes
- 1) inflammatory process in the alveolar spaces – alveolitis
- 2) scarring – fibrosis
- Both processes often occur simultaneously
- Granuloma : localized collection of cells called epithelioid histocytes (phagocytic or macrophage), generally accompanied by T-lymphocytes, multinucleated giant cells. Noncaseating in interstitial lung diseases. Examples include hypersensitivity pneumonitis and sarcoidosis
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
Imaging
- 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
Dx & Px
- 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
- 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
Interstitial lung disease
- Complicating Connective Tissue Disease
- Rheumatoid Arthritis
- Systemic Lupus Erythematosis
- Progressive systemic sclerosis (Scleroderma)
- Polymyositis-dermatomyositis
- Sjogren’s Syndrome
- Overlap Syndromes
Interstitial lung disease
Connective Tissue Disorders
- Connective Tissue Disorders
- Usually patients have evidence of underlying disease first, but sometimes lung manifestations can proceed diagnosis by several years
- Pulmonary involvement is more common than clinically suspected
- Often UIP, but sometimes NSIP, or COP
- Lower lobe more common than upper lobe disease
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
Pulmonary Langerhans Cell Histiocytosis
- Starts as a peribronchiolar distribution and later becomes more diffuse
- Disease occurs almost exclusively in smokers
- Chest x-ray
- Nodular or reticulonodular disease
- Upper lobe prominent
- HRCT
- Small cysts in addition to the nodular and reticulonodular changes
- Cysts may rupture and cause pneumothorax
- Some cases extensive honeycombing
Pulmonary Langerhans Cell Histiocytosis
Natural Hx
- Natural history is variable
- Self limited in some with radiographic and functional changes stabilizing over time, especially with smoking cessation
- In others, more extensive disease and significant functional impairment
- No clearly effective treatment
- Corticosteroids used if smoking cessation alone is ineffective
•
•
Lymphangioleiomyomatosis
- Rare pulmonary disease
- Characterized by proliferation of atypical smooth muscle cells around lymphatics, blood vessels, and airways, accompanied by numerous small cysts throughout the pulmonary parenchyma
- Occurs almost exclusively in women of childbearing age
- Develops in 30-40% of female patients with the genetic condition tuberous sclerosis complex
Lymphangioleiomyomatosis
Clinical Manifestation
- Clinical Manifestation
- Dyspnea and cough
- Vascular involvement may lead to hemoptysis
- Lymphatic obstruction may produce a chylous pleural effusion
- Airway involvement may lead to airflow obstruction
- Rupture of subpleural cysts can lead to spontaneous pneumothorax
Lymphangioleiomyomatosis
Imaging
- Chest x-ray
- Reticular pattern, cystic changes
- Lung volumes normal or increased
- HRCT
- Cystic disease throughout the pulmonary parenchyma
- Pulmonary Function Testing
- Obstructive disease, restrictive disease, or both
Goodpasture’s Syndrome
- Affects lungs and kidneys
- Patients have episodes of pulmonary hemorrhage, and pulmonary fibrosis may develop
- Patient have glomerulonephritis characterized by linear deposits of anti-glomerular basement membrane antibody
- Anti-GBM is an antibody against type IV collagen in their own GBM
- Anti-GBM cross reacts with the basement membrane of the alveolar wall leading to pulmonary manifestations
Goodpasture’s Syndrome
Tx
- Treatment
- Plasmapheresis is capable of directly removing anti-GBM antibodies from the circulation
- Immunosuppressive therapy such as prednisone or cyclophosphamide are given to decrease the formation of anti-GBM antibiodies in conjunction with the plasmapharesis
Wegener Granulomatosis
- Upper respiratory tract, lungs, and kidneys
- Upper respiratory tract and lungs – necrotizing small-vessel granulomatous vasculitis
- Kidneys with focal glomerulonephritis
- Chest x-ray
- Nodules, infiltrates, cavitation
- Diffuse interstitial lung disease is not characteristic
- cANCA +
Wegener Granulomatosis
Tx
- Treatment
- Cyclophosphamide
- Prednisone
Churg-Strauss Syndrome
- Systemic necrotizing vasculitis
- Affects upper and lower respiratory tracts
- Preceded by allergic disorders such as asthma , allergic rhinitis, sinusitis or drug reaction
- Peripheral and lung eosinophilia
- Increased immunoglobulin E levels
- Rashes
Churg-Strauss Syndrome
Imaging
Testing
Tx
- Chest x-ray
- Bilateral patchy, fleeting infiltrates
- Diffuse nodular infiltrates
- Diffuse reticulonodular infiltrates
- Biopsy
- Granulomatous angiitis or vasculitis
- Treatment
- Corticosteroids
Chronic eosinophilic pneumonia
- Pulmonary interstitium and alveolar spaces are infiltrated by eosinophils and to a lesser extent macrophages
- Clinical Manifestations
- Occurs over weeks to months
- Fever, weight loss, dyspnea, and productive cough
- Pulmonary infiltrates with a peripheral distribution and more suggestive of alveolar than interstitial disease
- Increased eosinophils in the peripheral smear
- BAL with increased eosinophils
Chronic eosinophilic pneumonia
- Treatment
- Dramatic response to corticosteroids within days to weeks
- Therapy must often be prolonged for months to prevent recurrence
Pulmonary alveolar proteinosis
- Primary pathologic process affects the alveolar spaces, not the alveolar cells
- Alveolar spaces are filled with a proteinaceous phospholipid material that represents components of pulmonary surfactant
•
Pulmonary alveolar proteinosis
- Clinical manifestations
- Dyspnea and cough
- Bilateral alveolar infiltrates
- HRCT crazy paving pattern produced by thickening of interlobular septa accompanied by ground –glass alveolar filling
- Superimposed to respiratory infections - Nocardia
- Treatment
- Whole-lung lavage
- Prognosis is good
Hypersensitivity Pneumonitis
- Hyperimmune respiratory syndrome caused by inhalation of a wide variety of allergic antigens that are usually organic
- Causative antigens include bacteria, fungi, protozoa, animal proteins, and reactive chemicals
- Treatment
- Identify causative antigen and avoid exposure
- Prevent progressive permanent lung damage
- Corticosteroids hasten resolution
Hypersensitivity Pneumonitis
•Suspect Hypersensitivity Pneumonitis
- Suspect Hypersensitivity Pneumonitis
- Intermittent pulmonary and systemic symptoms
- Progressive pulmonary symptoms with interstitial chest x-ray changes
- Non-resolving pneumonia
- Workplace exposures
- Agricultural and cattle farming
- Recreational exposures
- Bird keeping
- Home exposures
- Contaminated home ventilation
- Hot tubs
Hypersensitivity Pneumonitis
•Clinical Presentation
- Clinical Presentation
- Acute
- Abrupt onset of cough, dyspnea, fever, and chest pain following heavy exposure to the offending antigen
- Symptoms begin 4-6 hours after exposure
- Subside within 24 hours of removal from exposure
- Subacute
- More gradual development of symptoms
- Less severe intensity
- Chronic
- Insidious progressive dyspnea, cough, weight loss, and fatigue
- Most progress toward pulmonary fibrosis, with respiratory
Hypersensitivity Pneumonitis
•Professions and Hobbies Affected
- Professions and Hobbies Affected
- Farmers
- Bird keepers or breeders
- Woodworkers
- Office workers with forced-air ventilation
- Cheese makers
- Plastic industry workers
- Metal workers
- Painters/refinishers
- Lifeguards
- Machine workers
Hypersensitivity Pnemonitis
•Common etiologies
- Common etiologies
- Farming and agriculture – especially dairy cattle
- Thermophillic actinomycetes in moldy hay, grain, or silage
- Bird and Poultry Handling
- Animal proteins from droppings, feather, or serum proteins
- Pigeons, parakeets, budgerigars, canaries, chickens, ducks, and turkeys
- Ventilation and water-related contamination
- Humidifiers, hot-tubs, air conditioners, unventilated showers, or contaminated basements
- Thermophillic actinomycetes
- Mycobacterium avium-intracellulare complex organisms
Hypersensitivity Pneumonitis
Imaging
- Chest x-ray
- Acute disease diffuse reticulonodular infiltrates
- Chronic disease with diffuse interstitial fibrosis
- HRCT
- Ground glass opacities early
- Chronic with traction bronchiectasis, honeycombing, and fibrosis
- PFT’s
- Restriction, small lung volumes, decreased diffusion capacity
Sarcoidosis
- Sarcoidosis is a systemic granulomatous disease of unknown etiology characterized pathologically by the non-caseasting granuloma.
- Can effect almost any organ
- 90% of patients present with mediastinal or hilar lymphadenopathy and parenchymal lung disease
- Occurs at any age, but most commonly between the ages of 40-60
- Incidence 3.5 times higher in black Americans compared to white Americans
- Women have a higher incidence than men
•
Sarcoidosis
Involvement
- Pulmonary involvement frequent, but not necessary for the diagnosis
- Initial presentation may be an abnormal chest x-ray with mediastinal and hilar adenopathy
- 50% of patients have no symptoms at the time of diagnosis
Sarcoidosis
•Lofgren’s Syndrome
- Lofgren’s Syndrome
- Acute manifestation of sarcoidosis
- Erythema nodosum
- More common in women
- Arthritis
- More common in men
- Bilateral Hilar Lymphadenopathy
- Prognosis is favorable
Sarcoidosis
Etiology
•Sarcoidosis may also cause a more chronic disease leading to pulmonary fibrosis and increased morbidity and mortality
Sarcoidosis
Sx
- Symptoms
- General: fatigue, fever, night sweats, and weight loss.
- Pulmonary: Cough, dyspnea with exertion, wheeze, chest discomfort – 50% of patients have only respiratory symptoms
- Skin: rash, macules, papules, nodules, hyperpigmentation or hypopigmentation, erythema nodosum
- Ocular: gritty or dry eyes, pain, redness, and or blurred vision
Sarcoidosis
•Symptoms – continued
- Symptoms – continued
- Cardiac: arrhythmia, palpitations, near-syncope, syncope, lower extremity edema
- Nervous System: headaches, blurred vision, numbness, weakness, instability, seizures
- Gastrointestinal: epigastric pain, early satiety, RUQ pain, jaundice
- Musculoskeletal: swelling and joint stiffness, joint pain, muscle pain
- Upper Respiratory tract: nasal congestion, sinus pressure, nasal discharge