Interstitial lung disease Flashcards by Leslie Mancini

Interstitial Lung Diseases (ILD)

general

Collection of disorders that involves inflammation and scarring (fibrosis) of the lung interstitium (the space between the capillaryendotheliumand the alveolarepithelium
The lung becomes “stiff” (reduced distensibility) and compromises lung expansion

Causes
Idiopathic or secondary to connective tissue diseases, medications, malignancies, occupational exposure, or allergens

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ILD

pattern on spirometry

Restrictive pattern on spirometry
Normal FEV1/FVC ratio (> 0.70) and a reduction in TLC below 80% of the predicted value
Decreased diffusion capacity for carbon monoxide (DLCO)
Impaired gasdiffusionacross the alveolar membrane:

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Idiopathic pulmonaryfibrosis (IPF)

general and RF

Characterized by chronic, progressive, irreversiblefibrosis (“scar tissue”) of the lung parenchyma

Epidemiology:
Estimatedprevalencein the United States: 10–60 per 100,000
Occurs primarily in elderly individuals
Commonly diagnosed in the 50-60 years old
Men > Women

Risk factors: male, advanced age, history of tobacco use

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Idiopathic pulmonaryfibrosis

patho

The mechanism triggering IPF is poorly understood

Environmental exposure and possible genetic predisposition

Recurrent alveolar epithelial damage → type I pneumocytes release transforming growth factor beta1 → proliferation of type II pneumocytes → stimulate fibroblasts that are found in the interstitial tissue
Activated fibroblastsdevelop into myofibroblast (fibroblasts with smooth muscle cell properties)

Myofibroblast secrete:
Reticular fibers - a type of collagen which provides structural strength
Elastic fibers - provide the rubber-band like elasticity of the lungs

Failure of normal myofibroblastapoptosis→ accumulation of collagen leads to thickening of the interstitial layer

Consequences:
Restrictive lung - poor air in and out of the lung
↓gas exchange

Fundamental problem….too many myofibroblasts and too much collagen!

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Idiopathic pulmonaryfibrosis

clin man

progressive disease

Asymptomatic early in the disease process
Moderate to advanced stage:
Chronic dyspnea-Initially exertional, Progressive, eventually occurring at rest
Chronic nonproductive cough
Reduced exercisetolerance
Chest pain

Associated systemic symptoms (uncommon):
Fatigue
Low-grade fever
Weight loss
Myalgias

will lead to r sided heart failure and pulm HTN

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Idiopathic pulmonaryfibrosis

PE findings
Auscultation
secondary disease sx

Bibasilar fine inspiratory (“Velcro-like”) crackles on auscultation
End-inspiratory “squeaks” in advanced disease withbronchiectasis
Digitalclubbing
Cyanosis

Patients can present withpulmonary hypertension (PH) andcor pulmonale:
Pitting edema (pedal or sacral)
Jugular venous distention
Cyanosis
Split second heart sound
(this is later as disease progresses)

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Idiopathic pulmonaryfibrosis

Hx Dx
Med use

Diagnosed by a combination of radiologic, pathologic, and clinical investigations
Critical to obtain a complete patient history
Occupational history
Recreational history
Environmental history
Radiationexposure

Notable medications associated with pulmonary fibrosis:
Amiodarone
Bleomycin
Nitrofurantoin
Methotrexate

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Idiopathic pulmonaryfibrosis –

Diagnosis Spirometry

Pulmonary function test
Reveals ↓ lung volumes (restrictive pattern):
Vital capacity
Total lung capacity(TLC)
Forcedvital capacity(FVC)
Forced expiratory volume in 1 sec
FEV1/FVC ratio is greater than 80% (increased) due to a significant decrease in forced vital capacity (FVC)

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Idiopathic pulmonaryfibrosis

imaging

Chestx-ray
May look normal in early disease
Reticulonodular infiltrates
Bilateral, basal, and symmetrical

High-resolution CT scan
Significantly more sensitive and specific
Features (predominantly seen in the lower lobes):
Peripheral and subpleural reticular septal thickening
Tractionbronchiectasis
Honeycombing
Lung architecturaldistortion
Superimposed ground-glass opacities may be seen

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Idiopathic pulmonaryfibrosis

biopsy and labs

Lung biopsy- best for Dx
Surgical specimens can be obtained using video-assisted thoracoscopic surgery (VATS)
Supporting laboratory evaluation to exclude other causes ofILD and guide management:

Erythrocyte sedimentation rateand CRP
Antinuclearantibodies
Rheumatoid factorand anti–cyclic citrullinated peptideantibodies
Aldolaseand CK
Myositis-specificantibodies
Anti-SSA/Ro and anti-SSB/Laantibodies
Serum ACE level

pulmonologist would do this

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Idiopathic pulmonaryfibrosis

lifestyle mods

Smoking cessation
Vaccinations: influenza, Covid-19, and pneumonia

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Idiopathic pulmonaryfibrosis

Antifibrotic drugs
Approved for delaying progression
Do not significantly improvemortality

Oxygen therapy
Indicated when the patient’sresting or ambulatory oxygen saturation are < 88%

Lung transplant
Only definitive treatment
Bilaterallung transplantationis more commonly used than singlelung transplantation
Early referral should be considered

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Sarcoidosis

general

Multisystem inflammatory disease characterized by the formation ofnoncaseating granulomas that are most likely caused by a cell-mediated immune reaction
Etiology is undetermined but is most likely multifactorial
more common in african american women
Potential triggering exposure: environmental exposure or infectious agent
Genetic predisposition

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sarcoidosis

pulmonary or extrapulmonary

Pulmonary sarcoidosisis a restrictive interstitial lung disease with granuloma formation in the:
Lungs(90% ofpatients)
Thoraciclymph nodes(hilar and mediastinal)

Extrapulmonary sarcoidosisis characterized by granuloma formation in:
Eyes – uveitis
Skin – erythema nodosum; macular or papular lesions
Joints
Heart – arrhythmias
Kidney
CNS andperipheral nervous system
Exocrine glands

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sarcoidosis

Patho

Phagocytosisof a newantigenbyantigen-presenting cells (macrophagesanddendritic cells)
Activated macrophages present the antigento helper T cellsvia the HLA-CD4 complex
Activated T cellsandmacrophagesrelease inflammatory mediators (Th1response):
Interleukin 2 (IL-2)
Interferon gamma
Tumornecrosisfactor (TNF)
Othercytokinesandchemokines
Inflammatory mediators causemacrophagesto fuse into multinucleatedgiant cells
Unable to destroy the antigens, the multinucleatedgiant cellswall them off →noncaseating granulomaformation
Fibroblasts are recruited and surround granulomas and may progress tofibrosis

NON CASEATING

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Sarcoidosis

CLin man

Initially progresses slowly, with few symptoms
Symptoms appear as an increasing number of granulomas affecting organ function
Cutaneous sarcoidosisis known as one of the “great imitators”\

Sarcoidiosis

imaging

Chestx-ray
Bilateral hilarlymphadenopathy(classic finding)
Bilateral reticulonodular infiltrates (often upper lobes)
Honeycombing (end-stage disease)- not for exam though
Chest CT scan
Bilateral hilar and mediastinallymphadenopathy
Small centrilobular parenchymal nodules
Ground-glass opacification

sarcoidosis

BAL

Bronchoalveolar lavage (BAL)
Obtained primarily to exclude alternative diagnosis
Lymphocytosis (T-cells)≥ 25% suggests a granulomatous process

sarcoidosis

labs

Labs
Elevated ACE level
Measure of the level of angiotensin-convertingenzyme in the blood
Elevated due to additional production by activated macrophages and epithelioid cells in the granulomas

sarcoidosis

biopsy

Gold standard for diagnosis
Obtained from the most accessible affected site (skinlesions)
Lung biopsies can be obtained via bronchoscopy or surgically
Key finding: well-defined noncaseating granulomas
Noncaseating: no centralnecrosis
Multinucleated giant cells

sarcoidosis

Minimal symptoms → observation
Most symptoms resolve spontaneously within a few weeks
Complete remission from sarcoidosis typically happens within a few years
Moderate-severe symptoms
Corticosteroids: first-line therapy
Steroid-sparing agents:second-line therapy:
Azathioprine
Methotrexate
Lung transplantation:in cases of advanced pulmonaryfibrosis

Pneumoconiosis

Pneumoconiosis is an occupational disease that results from the inhalation and deposition of mineral dusts and other inorganic particles in the lung; categorized according to the type of causative particle involved or by the type of response provoked
Asbestosis
Silicosis
Coal Worker’s Pneumoconiosis

Exposure has greatly decreased due to the enforcement of environmental rules and regulations

Pneumoconiosis

patho

Inhaled toxic fibers/dust cannot be metabolized by the body and accumulate in the alveolar ducts
Particles ofappropriate sizeto be retained in lung (1-5μm)
The fibers are engulfed bymacrophages, which undergo lysis and releasecytokines
Cytokines induce an inflammatory reaction, producingairway obstruction and stimulatingfibroblasts
Fibroticscarring leads to thickening of the airways, reducedelasticity, and impairedgas exchange

leading to restrictive pattern

Pneumoconiosis

general S/Sx

Progressive exertionaldyspnea
Dry cough
May be productive in the morning, with clear-to-white sputum
Chest discomfort due to heart failure following pulmonary hypertension
Inspiratoryralesor crackles
Digitalclubbingin advanced disease

Persistent cough with sputum and wheezing is unusual, but may be present if there has been associated cigarette smoking

# pneumoconiosis Dx

Documented **exposure history** to a known toxic agent A typical **latent period** between exposure and symptoms **Clinical and radiological features** compatible with the known features of the disease **Exclusion of any other disease** that could explain the findings

# pneumoconiosis Tx

No definitive treatment for pneumoconiosis, regardless of the clinical stage Immediate cessation of exposure is recommended **Cessation of tobacco smoking** Management is largely **supportive** and focuses on the prevention of further progression and complications (oxygen is dyspnea) **Prophylactic vaccinatio**n against influenza, COVID-19 and pneumococcal pneumonia Oxygen therapy is often necessary to relieve dyspnea **Early systemic oral glucocorticoid therapy** may relieve symptoms, improve lung appearance on imaging, and normalize pulmonary function testing scores Lung transplantation has been performed for advanced pneumoconiosis with respiratory failure, but evidence on patient outcomes is lacking- not endorsed

# Asbestosis general

ILD caused by inhalation of asbestos fibers Carcinogen Known to cause mesothelioma, lung cancer **(bronchogenic carcinoma**), laryngeal cancer and ovarian cancer Historically been used in construction, shipping, mining, and aerospace engineering commercial use because of their high electrical and thermal resistance and low cost Dose-dependent disease Most prevalent in disciplines where the intensity of exposure is high Cigarette smoking accelerates disease progression Onset after 10-20 years of exposure

# Asbestosis Xray and CT

Chest x-ray Diffuse irregular opacities with a fine reticular pattern **Calcified or noncalcified pleural plaques** Chest CT scan Reticular opacities in the lower lung zones Interlobular pleural thickening Calcified or noncalcified pleural plaques Bronchiectasis Pleural effusion

# Asbestosis BAL

**Bronchoalveolar lavage (BAL) Shows asbestosis bodies** dx depends on finding these

# asbestosis

# Silicosis general

ILD caused by inhalation of crystalline silica dust Most common form of occupational lung disease Silica exposure Mining, sandblasting, quarry, ceramics, and foundry workers; and in grinding, stone cutting, fiberglass, and glass manufacturing Onset after > 10 years of exposure but can manifest after several months of intense daily exposure Silica is known to weaken cell-mediated immunity Increased susceptibility to infections, especially tuberculosis When assessing patients for silicosis, screen for **tuberculosis**

# Silicosis Dx | start w imaging then BAL

Chest x-ray Multiple, small nodular opacities (1-10 mm) in **the upper lung fields** Calcification of nodules Chest CT scan **Calcification of the periphery of mediastinal and hilar lymph nodes (referred to as eggshell calcifications)** Pleural thickening **Bronchoalveolar lavage (BAL) Silica-laden macrophages**

# silicosis

"eggshell calcification"

# Coal Worker’s Pneumoconiosis general

ILD caused by exposure to coal dust Onset after > 10 years of exposure Large amorphous black masses develop that occasionally have a liquified centers

# Anthracosis general

Chronic, low level environmental exposure to coal dust or wood smoke Black discoloration of the bronchial mucosa Generally considered benign; can progress to anthracofibrosis (fibrotic changes and destruction of bronchial walls) | usually benign, milder col miners pneumoconiosis

# coal miners Dx | imaging to BAL

Chest x-ray Small (1-5 mm) round nodular opacities in the **upper lung fields** Occasional appearance of **reticular or reticulonodular opacities** Conglomerate masses in advances disease Chest CT scan Diffuse (typically perilymphatic) distribution of small nodules throughout the lungs, which tend to favor the upper lungs **Bronchoalveolar lavage (BAL) Black pigmented macrophages** ## Footnote Silicosis and CWP are not easily distinguished from one another on imaging studies