Classification and Diagnostic Approach
Pulmonary and Critical Care Medicine · Diffuse Parenchymal Lung Disease 🎯 Practice these cards
Diffuse parenchymal lung disease (DPLD), a term used largely interchangeably with ____, is a heterogeneous family of more than ____ nonmalignant disorders that injure the lung parenchyma through varying mixtures of ____.
Diffuse parenchymal lung diseases (DPLDs) — a term used largely interchangeably with interstitial lung diseases (ILDs) — are a large, heterogeneous family of more than 200 nonmalignant disorders that injure the lung parenchyma through varying mixtures of inflammation and fibrosis.
The overall prevalence of DPLD is estimated at roughly ____ per 100,000 persons; ____, ____, and ____ are consistently among the most common forms.
The overall prevalence of DPLD is estimated at roughly 70 per 100,000 persons; among the many forms, idiopathic pulmonary fibrosis (IPF), sarcoidosis, and connective tissue disease (CTD)–associated ILD are consistently among the most common.
The DPLD classification scheme has three groups: DPLDs with ____, DPLDs of ____ (e.g., IPF, sarcoidosis), and ____ with distinctive clinical signatures (e.g., LAM, pulmonary alveolar proteinosis).
The clinically useful classification divides DPLDs into those with an identifiable cause (drugs, smoking, radiation, chronic aspiration, pneumoconioses, CTDs, hypersensitivity pneumonitis), those that are idiopathic/unknown (IPF, idiopathic NSIP, cryptogenic organizing pneumonia, AIP, sarcoidosis), and a third bucket of rare diseases with distinctive clinical signatures (LAM, chronic eosinophilic pneumonia, pulmonary alveolar proteinosis).
The most common presentation of a DPLD is ____ with ____.
The most common presentation of a DPLD is subacute to chronic exertional dyspnea with a nonproductive cough; the initial evaluation should also consider common mimics (heart failure, diffuse infection such as Pneumocystis pneumonia, and malignancy) before narrowing to DPLD subtypes.
Resting pulse oximetry can be deceptively normal in DPLD; a desaturation of greater than ____ with ambulation reflects ____ — a physiologic hallmark of DPLD.
Resting oximetry can be deceptively normal in DPLD. A desaturation of greater than 4% with ambulation reflects diffusion limitation — a physiologic hallmark of DPLD — so oximetry must be assessed with exertion, not only at rest.
A normal chest radiograph ____ DPLD — the plain film can be normal in minimal or early disease (and reportedly in up to ____ of DIP cases); clinical suspicion should trigger ____ instead.
A normal chest radiograph does not rule out DPLD: the plain film can be entirely normal in minimal or early disease — and even in some established forms (reportedly normal in up to 20% of DIP cases). Clinical suspicion should trigger HRCT, not reassurance from a clear film.
Complete PFTs in DPLD typically show a ____ pattern — reduced ____ with symmetrically reduced FEV1 and FVC — along with reduced ____, which may precede any fall in lung volumes.
Complete PFTs in DPLD typically show a restrictive pattern — reduced total lung capacity with symmetrically reduced FEV1 and FVC — along with a reduced DLCO, which may precede any fall in lung volumes; serial FVC decline correlates with increased mortality.
____ of the chest is the imaging modality of choice for the evaluation of DPLD and, in the right clinical context, can be diagnostic — sparing the patient the risk of ____.
Noncontrast high-resolution CT (HRCT) of the chest is the imaging modality of choice for the evaluation of DPLD and is standard of care in the initial workup; in the right clinical context it can be diagnostic — sparing the patient the risk of biopsy.
The ATS/ERS/JRS/ALAT algorithm sorts HRCT findings into four categories: UIP, ____, ____, and ____; a definite UIP pattern is diagnostic of ____ without tissue confirmation.
The ATS/ERS/JRS/ALAT diagnostic algorithm sorts HRCT findings into four categories: UIP, probable UIP, indeterminate for UIP, and alternative diagnosis. A definite UIP pattern is diagnostic of IPF without tissue confirmation; the 2022 update allows a probable UIP pattern to diagnose IPF without biopsy in the appropriate clinical context.
A definite UIP pattern on HRCT consists of subpleural, basal-predominant ____ with ____, with or without ____, and no atypical features.
A definite UIP pattern on HRCT consists of subpleural, basal-predominant reticulation with honeycombing, with or without traction bronchiectasis, and no atypical features; extensive ground-glass opacity, micronodules, mosaic attenuation, or upper-lung predominance should raise suspicion for an alternative diagnosis.
UIP is a ____, not a diagnosis: identical findings appear in CTD-associated ILD, asbestosis, and ____; IPF can be labeled only after ____ are excluded.
UIP is a pattern, not a diagnosis: identical imaging and histology appear in CTD-associated ILD, asbestosis, and chronic hypersensitivity pneumonitis. IPF can be labeled only after known causes are excluded — which is why exposure history and serologic testing must precede any confident diagnosis.
For newly detected DPLD of apparently unknown cause, ATS guidelines recommend serologic testing to exclude ____: the panel includes CRP, ESR, ____, ____, a myositis panel, and ____.
For newly detected DPLD of apparently unknown cause, ATS guidelines recommend serologic testing to exclude CTD-associated DPLD: C-reactive protein, erythrocyte sedimentation rate, antinuclear antibodies, rheumatoid factor, a myositis panel, and anti–cyclic citrullinated peptide (anti-CCP) antibodies — worthwhile even when history and examination are silent.
When PFTs and HRCT are insufficient, the biopsy decision should be deliberated within a ____, which is treated as the diagnostic gold standard; surgical lung biopsy carries a short-term mortality of up to approximately ____.
When PFTs and HRCT are insufficient to establish a diagnosis, tissue may be required; the decision should be deliberated within a multidisciplinary team (thoracic radiologist, thoracic surgeon, DPLD-experienced pulmonary specialist), and MDD is treated as the diagnostic gold standard. Surgical lung biopsy carries a short-term mortality of up to ~5% (higher in IPF and acute presentations).
Progressive pulmonary fibrosis (PPF) is defined as at least ____ of three criteria within one year: worsening respiratory symptoms, physiologic progression (absolute FVC decline ≥____ or DLCO decline ≥____), or radiologic progression.
Progressive pulmonary fibrosis (PPF) is a unifying label for any non-IPF ILD that worsens — defined as at least two of three within one year: worsening respiratory symptoms, physiologic progression (absolute FVC decline ≥5% or DLCO decline ≥10%), or radiologic progression. The 2022 guideline conditionally recommends nintedanib for PPF (based on the INBUILD trial).
The 2025 ERS/ATS update introduces ____ as an overarching airway-centered category, renames DIP as ____, and replaces AIP with ____.
The 2025 ERS/ATS statement merges idiopathic and secondary interstitial pneumonias into one unified scheme: it introduces bronchiolocentric interstitial pneumonia (BIP) as an overarching airway-centered category, renames desquamative interstitial pneumonia (DIP) as alveolar macrophage pneumonia (AMP), and replaces acute interstitial pneumonia (AIP) with idiopathic diffuse alveolar damage (DAD).
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