Twenty Four Flashcards
(32 cards)
What 3 hallmark clinical features do ILDs usually present with?
Regardless of the specifi c etiology of an ILD
and its pathophysiological mechanisms, the presenting clinical
manifestations usually include three hallmark features: (1)
progressive dyspnea on exertion; (2) restrictive physiology on
pulmonary function tests; and (3) diffuse reticular infi ltrates
or ground-glass opacities on chest radiographs or thoracic
CT imaging studies.
List the 7 idiopathic interstitial pneumonias and their histological pattern
Usual interstitial pneumonia
Idiopathic pulmonary fi brosis
Nonspecifi c interstitial pneumonia
Nonspecifi c interstitialpneumonia
Organizing pneumonia
Cryptogenic organizing pneumonia
Diff use alveolar damage
Acute interstitial pneumonia
Respiratory bronchiolitis
Respiratory bronchiolitis interstitial lung disease
Desquamative interstitial pneumonia
Desquamative interstitialpneumonia
Lymphoid interstitial pneumonia
Lymphoid interstitial pneumonia
What is the epidemiology of IPF? What are the HRCT findings like? What is the histopathology like? What is the median survival?
Idiopathic pulmonary fi brosis (IPF) is the most important
and common idiopathic interstitial pneumonia and, in
many ways is a prototypic ILD and restrictive lung disease
with respect to symptoms, physical fi ndings, and laboratory
features. IPF affects at least 200,000 persons in the United
States, whose median survival is 3-5 years from diagnosis.
The exact cause of IPF is not known. Interestingly, 0.5%-
3.7% of cases of IPF are familial, and 60% of patients diagnosed
with this disorder have a positive history of smoking.
The incidence of IPF increases signifi cantly in older adults,
being most common between the ages of 50 and 70 years.
High-resolution chest CT (HRCT) fi ndings in IPF may be
pathognomonic when demonstrating patchy, heterogeneous
and subpleural, peripheral reticular opacities and septal thickening
usually found in conjunction with honeycombing and
traction bronchiectasis (Fig. 24.1). Histopathologically, IPF
is a common although not exclusive idiopathic etiology for
usual interstitial pneumonia (UIP).
What are the presenting symptoms of IPF? What is found on PFTs?
Presenting symptoms
in IPF include dyspnea on exertion in 90% of patients and
nonproductive cough in >70% of subjects. Bibasilar inspiratory
Velcro-like crackles predominate in 85% of IPF patients
on physical examination whereas digital clubbing occurs in
at least 25% (Chap. 14). Pulmonary function test abnormalities
include restrictive ventilatory limitations characterized by a normal or increased FEV1/FVC ratio together with a
TLC that is <80% of predicted or the lower limit of normal
(LLN). Characteristically, the single breath DLCO is reduced,
and patients manifest mild to moderate arterial hypoxemia or
decreasing SaO2 during exertion (Chaps. 16 and 17).
What are some predictors of reduced survival in IPF? What are the causes of death?
Predictors of reduced survival in IPF include coexisting
emphysema and the presence of pulmonary hypertension as
refl ected by elevated PPA estimated using transthoracic echocardiography
or documented during right heart catheterization.
Physiological predictors are reduced FVC, TLC, and DLCO at
the time of diagnosis and then further declines in FVC and DLCO
over the succeeding 6-12 months. Additionally, a signifi cantly
reduced distance during the six-minute walk test (6-MWT)
and exertional decline in Sao2 correlate with increased mortality.
Causes of death in IPF include coronary artery disease, lung
cancer, infection, and pulmonary embolism.
Describe the acute exacerbations of IPF.
IPF is generally a chronic and relentlessly progressive
disorder. However, acute and frequently fatal exacerbations
can occur at any time and are increasingly recognized
as a major cause of death during which rapid progression of
disease occurs within 4 weeks. Such acute exacerbations of
IPF are not related to the severity of underlying PFT abnormalities,
and are often heralded by low-grade fever, fl u-like
symptoms, and worsening cough with dyspnea. Such fi ndings
occur in association with severe arterial hypoxemia and newly
developing diffuse radiographic opacities that are superimposed
on the baseline reticular pattern, often in the absence of
infectious pneumonia, heart failure, pulmonary thromboembolism,
or sepsis. Histopathologically, diffuse alveolar damage
(DAD) is generally found in patients with a background of
UIP. The rate of acute exacerbations ranges from 10% to 15%
per year and the risk factors are unknown. These exacerbations
carry a hospital mortality rate of 78%, and recurrence
among survivors of another acute exacerbation is common
and usually results in death.
What is the pathogenesis of sarcoidosis in the lungs? What is the epidemiology? Describe the 4 stages of chest radiographic findings.
Sarcoidosis is a systemic disorder that is characterized by the
formation of non-necrotizing, well-formed granulomas in
multiple organ systems. With respect to the lungs, T-helper
cell (CD4+) lymphocyte-mediated infl ammation plays a key
pathogenetic role. Sarcoidosis is a relatively common cause
of ILD in young and middle-aged adults, but not all patients
with sarcoidosis have pulmonary symptoms. Regardless,
there is usually incidental radiographical evidence of lung
and intrathoracic lymph node involvement, which is classically
distinguished by four stages using standard chest x-rays
(Table 24.3; Figs. 24.2 through 24.5).
I Bilateral hilar adenopathy
II Bilateral lymphadenopathy and reticulonodular
infi ltrates/opacities
III Bilateral reticulonodular infi ltrates/opacities
IV Fibrocystic changes with bullae, upper lobe
fi brotic scarring, and upward hilar retraction
List 7 CT disorders with lung abnormalities. What are the pulmonary radiographic and pathologic findings like? How do you differentiate them from idiopathic interstitial pneumonias?
The radiographical and histopathological spectra of ILD associated
with the connective tissue diseases systemic lupus erythematosis
(SLE), polymyositis-dermatomyositis (PM-DM),
mixed connective tissue disease, rheumatoid arthritis (RA),
progressive systemic sclerosis (PSS; either the diffuse form
or CREST variant), Sjögren’s syndrome, and ankylosing spondylitis encompass all of the patterns observed in the idiopathic
interstitial pneumonias. Consequently, the clinical history,
physical examination and results of specifi c laboratory
serologic tests are especially important.
What is the progression of lung symptomology in pts. with CT disorders? What histopathological patterns are found with the different CT disorders?
Generally speaking, development of ILD in patients
with connective tissue diseases may precede rheumatological
symptoms and signs; alternatively, pulmonary involvement
may occur concomitantly with, or follow, the onset of
rheumatic disease. Nonspecifi c interstitial pneumonia is the
most common form of ILD found in the setting of connective
tissue diseases, occurring in up to 80% of patients with
PSS, Sjögren’s syndrome, and PM-DM. However, a UIP-like
pattern as also seen in IPF frequently predominates in RA.
Although ILD secondary to connective tissue diseases is generally
a chronic process, acute, rapidly progressive presentations
of ILD may complicate the clinical picture, especially
SLE and PM-DM. Such rapid-onset ILD, typifi ed by acute
SLE pneumonitis, may simulate infectious pneumonia and/or
acute lung injury/acute respiratory distress syndrome.
List 3 eosinophilic lung disorders? Which is the most common?
These chronic ILD disorders are characterized by a pathological
infl ux of eosinophils into the pulmonary interstitium and
distal airspaces and are exemplifi ed by acute eosinophilic
pneumonia, Löffl er’s syndrome and by chronic eosinophilic
pneumonia. Löffl er’s syndrome, also termed simple
pulmonary eosinophilia, is the commonest eosinophilic lung
disorder.
What is the presentation of Lofflers syndrome like? How does it progress? What is the presentation of chronic eosinophilic pneumonia like? Which pts. does it occur in? What radiographic findings are there?
It frequently complicates helminthic infection or
drug reactions and manifests clinically by cough, wheeze, and
dyspnea with peripheral blood eosinophilia and transitory pulmonary
infi ltrates that resolve spontaneously and do not recur.
In contrast, chronic eosinophilic pneumonia classically occurs in
middle-aged female asthmatic patients, usually in conjunction with fever, blood eosinophilia, and interstitial pulmonary infi ltrates.
In at least 25% of patients with chronic eosinophilic
pneumonia, pulmonary infi ltrates occur in a pattern that is the
reversal of shadows typically seen in pulmonary edema. Here
the infi ltrates occur in the peripheral and subpleural locations
of the lungs, with relative sparing of the central and perihilar
areas, where pulmonary edema from other causes is usually
fi rst manifest (Fig. 24.6).
What is hypersensitivity pneumonitis? What is the etiology? What is the histology like? What is the development and progression of symptoms like?
ILD from chronic hypersensitivity pneumonitis, also known as
extrinsic allergic alveolitis, is a granulomatous process that
results from repeated inhalation and sensitization to a large
number of diverse organic antigens including, for example,
those related to specifi c bacteria as typifi ed by farmer’s lung,
mushroom worker’s lung, and bagassosis involving moldy
sugar cane in which thermophilic bacteria play a role, or animal
proteins from feathers or avian droppings as in bird breeder’s
disease. This ILD can also result from inhalation and sensitization
to low molecular weight chemical antigens such as isothiocyanates
in industrial workers. The development of chronic
hypersensitivity pneumonitis may be occult and slowly progresses
over time with continuing inhalational exposures until symptoms
occur, or may follow episodes of acute hypersensitivity
pneumonitis which typically occur 4-12 hours after exposures.
What are two vasculitides that involve the lung? What is the clinical course like?
Systemic disorders of immune regulation characterized by
necrotizing vasculitis may involve the lungs to result in ILD and
restrictive pulmonary dysfunction. Examples of such disorders
include necrotizing granulomatous vasculitis (Wegener’s granulomatosis)
and microscopic polyangiitis. Notably, patients
with these disorders may have more than one cause of ILD, since the clinical course may include episodes of diffuse alveolar
hemorrhage and pulmonary drug toxicity.
What is pneumoconiosis? What is an important concept concerning their timeline? What are etiologies along with their clinical features?
Occupational and environmental inhalational exposures to
inorganic dusts are the primary causes of pneumoconiosis
manifesting as ILD (Table 24.4), the majority of which occur
in men. An important concept is that ILD from pneumoconiosis
may have a prolonged latency interval, which in the case
of asbestosis may be 15-20 years following initial exposure.
Asbestos
Lower lobe interstitial infi ltrates
Pleural, pericardial calcifi cation
Silica
Nodular coalescing infi ltrates mid-upper lungs
Increased susceptibility to tuberculosis
Coal dust
Small rounded opacities
May develop into progressive massive fi brosis
Beryllium
Interstitial infi ltrates & intrathoracic adenopathy
Similarity to sarcoidosis
Hard metal dusts (eg, cobalt, tungsten)
Lower lobe interstitial infi ltrates
Multinucleated giant cells on histopathology
What is DAH? What is it associated with? How does it simulate ILD? What diseases is it common in? Describe the symptoms. How is the diagnosis made?
Diffuse alveolar hemorrhage (DAH) associated with either
alveolar infl ammatory capillaritis or bland DAH simulates
ILD by causing dyspnea and radiographically by producing
interstitial infi ltrates and/or increased ground glass opacities on
chest CT scans. DAH is a common interstitial process in SLE
as well as in other “pulmonary-renal syndromes” such as mixed
connective tissue disease, Goodpasture’s syndrome, and pulmonary
vasculitides including microscopic angiitis (Fig. 24.7).
DAH may occur with minimal or absent hemoptysis in as many as one-third of patients, since the bleeding may remain localized to the respiratory (alveolar) zone of the lungs. The diagnosis of DAH is supported by progressively greater bloody recovery of sequentially instilled bronchoalveolar lavage fl uid during fi beroptic bronchoscopy (Chap. 18).
What is one of the pathogeneses of drug-induced pulmonary disease? What are some examples of drugs that would cause it? How is it distinguished from other ILDs?
Drug-induced pulmonary disease covers a broad spectrum of reactions
of the lungs that includes parenchymal scarring culminating
in ILD. Adverse pulmonary reactions may occur: to chemotherapeutic
agents (bleomycin, busulfan, cyclophosphamide, etc); to antibiotics such as nitrofurantoin; to anti-infl ammatory
agents including gold, penicillamine, and methotrexate; and
to other agents. Apart from a history of receiving one of these
or other agents, there are no unique clinical fi ndings, radiographic
features, or physiological abnormalities to distinguish
drug-induced ILD from other categories of ILD. Consequently,
careful attention must be given to all current and previous
drugs the patient with ILD has received in order to make a
timely diagnosis.
What is amiodarone? Why is it a significant cause of drug-induced pulmonary disease? What are the chief symptoms of this? What exam findings are there? Radiological findings? BAL findings? Treatment? Prognosis?
Among drugs associated with diff use ILD, the antiarrhythmic
amiodarone is important given its frequency
of clinical use, very long mean elimination half-life
(58 days), and lack of signifi cant metabolism by liver or
kidneys. Based on the daily dose, up to 4%-6% of patients
receiving amiodarone may develop pulmonary toxicity
in the form of interstitial pneumonitis that progresses to
pulmonary fi brosis. Chief symptoms are insidious onset of nonproductive cough, progressive dyspnea on exertion, and low-grade fever; physical exam reveals inspiratory crackles. Radiological fi ndings include initial asymmetric or unilateral interstitial or alveolar infi ltrates; these progress to diff usely involve the lungs. Characteristically, a bronchoalveolar lavage or lung biopsy reveals foamy, phospholipid-laden macrophages, but such fi ndings indicate only exposure to the drug and not toxicity. Treatment consists of drug withdrawal and in selected instances, administration of corticosteroids. Despite these therapeutic maneuvers, fatal outcomes remain common.
What is LAM? What is the pathophys? In which pts does it occur? What are the PFT findings? Why? What radiographic findings are there?
Lymphangioleiomyomatosis (LAM) is a rare form of ILD
caused by abnormal smooth muscle proliferation involving
the alveolar septae, bronchioles, and lymphatic vessels
that occurs sporadically in females of child-bearing age. Of
note, despite the apparent ILD, LAM results in small airways
obstruction and thus, an obstructive pattern on pulmonary
function tests rather than the anticipated restrictive pattern.
A characteristic radiographic feature is the combination of
bilateral interstitial opacities and generalized pulmonary cyst
formation.
What is pulmonary langerhans cell histiocytosis? What characterizes it? In which pts. is it normally seen? What does chest x-ray show? What develops frequently?
Pulmonary Langerhans’ cell histiocytosis (granulomatosis)
is a rare disorder accounting for <5% of ILD cases and
characterized by interstitial pulmonary fi brosis or extensive
cyst formation that is usually seen in smokers. Chest x-rays
typically show diffuse reticular markings, reticulonodular
infi ltrates, and/or cysts representing dilated bronchi or bronchioles;
there is a predilection for middle and upper lung
zones. Pneumothoraces develop frequently. In later stages
of the disease, the fi brosis can be extensive.
What is PAP? What causes it? Which stain is helpful? What is shown radiographically?
Pulmonary alveolar proteinosis (PAP) is an unusual
ILD in which there is increased secretion and/or abnormal
processing by alveolar macrophages of surfactant-derived
phospholipids which accumulate in alveolar spaces and stain
positive by the periodic acid-Schiff (PAS) reagent. Defi -
ciency or inactivation of GM-CSF plays a causal role in autoimmune
forms of the disease. PAP is not a specifi c disease
but rather a syndrome depending on whether an underlying
disease associated with surfactant dysfunction is present.
Radiographically, PAP shows geographic regional variation
in its interstitial involvement, with map-like alternations of
increased and decreased tissue density (Fig. 24.8).
What are the clinical features of Restrictive lung diseases? Exam findings? Symptoms?
Regardless of etiology, patients with restrictive lung disease
present with progressive dyspnea on exertion and nonproductive
cough. Dyspnea in ILD results from restrictive lung
impairment with decreased lung compliance secondary to
interstitial fi brosis, along with increased inspiratory muscle
work and O2 consumption during breathing, particularly during
exertion. Constitutional symptoms such as low-grade fever
and malaise may also be present at the onset of disease.
The classic fi nding on physical exam in most forms of
ILD is bibasilar inspiratory crackles and may be present in
a symptomatic patient with even an apparently normal chest
radiograph. Clubbing of the digits usually indicates advanced
fi brotic lung disease and is present in 25%-50% of patients with
ILD at initial presentation. An important exception however is
drug-induced ILD, in which clubbing is generally not observed.
In known cases of ILD, the new onset of clubbing may indicate
the concomitant development of lung cancer. Cyanosis accompanying
severe hypoxemia may occur in advanced restrictive lung
disease. Because of chronic arterial hypoxemia, patients with
restrictive lung disorders are at risk for development of pulmonary
hypertension and resultant right ventricular hypertrophy.
What are some important things to investigate with the medical history?
Considering the impact of environmental inhalational exposures,
pneumoconioses, and drug-induced pulmonary reactions in the
pathogenesis of restrictive lung diseases, a comprehensive medical
history with a special focus on the patient’s environmental
and occupational history is important. So too is an evaluation
of all the patient’s current medications and their duration of
use. Likewise, determining the tempo of progression of respiratory
symptoms is helpful with respect to differential diagnostic
considerations. For example, alveolar hemorrhage syndromes
are likely to present in an acute manner, whereas IPF or sarcoidosis
typically evolve more chronically.
When are lab tests useful for diagnosing ILDs? Which ones?
By themselves, laboratory tests are of limited utility in establishing
a diagnosis of ILD. Results must be integrated with
clinical fi ndings, thoracic imaging studies, and histopathological
results when available. Nonetheless, focused testing can
be useful in narrowing the differential diagnosis in the appropriate
setting. For example, peripheral blood eosinophilia
may be an important clue to the presence of an underlying
eosinophilic lung disorder or drug-induced pulmonary reaction.
Serological blood testing for specifi c connective tissue
disorders such as rheumatoid arthritis and SLE is similarly
helpful, whereas anti-neutrophil cystoplasmic antibody
(ANCA) studies to diagnose Wegener’s granulomatosis and
microscopic polyangiitis, respectively, and anti-glomerular
basement membrane antibody determination to diagnose Goodpasture’s syndrome assist in pinpointing the cause of
alveolar hemorrhage syndromes.
What are the PFT results in ILDs? In other restrictive lung diseases? Which levels confirms the diagnosis? What ABG results are expected? When are exercise studies useful and what do they unveil?
The classic fi ndings of ILD are a restrictive ventilatory pattern
and a decrease in the DLCO (Chap. 16). This restrictive
ventilatory limitation is characterized by a dual reduction in
the FEV1 and FVC with a correspondingly normal or elevated
FEV1/FVC ratio. In this setting, a total lung capacity (TLC)
fi nding ≤80% of predicted values confi rms the diagnosis of
restrictive lung disease. Whereas the presence of ILD is consistent
with a reduction in both the TLC and the DLCO, chest
wall and neuromuscular disorders are generally associated
with a reduced TLC but a normal DLCO.
Arterial blood gases and specifi cally the Pao2 or Sao2
may be normal at rest in patients with ILD. However, respiratory
alkalosis with hypocapnia and mild-to-moderate arterial
hypoxemia and widening of the (A − a) Po2 gradient develop
with progressive disease. In patients who have normal gas
exchange at rest, cardiopulmonary exercise tests are especially
useful in unmasking gas exchange abnormalities, principally
exertional O2 deoxygenation by oximetry. Exercise physiology
studies may further reveal an elevation in the VD/VT, a widened
(A − a) Po2 gradient, and arterial hypoxemia in conjunction
with progressive tachypnea.
