Acute Consolidation
Pneumonia (by far the most common cause of acute consolidation).
Aspiration, consolidation may appear heterogeneous from mucus plugging.
Pulmonary hemorrhage (primary pulmonary hemorrhage or aspiration of hemorrhage).
Adult respiratory distress syndrome (ARDS), which is noncardiogenic pulmonary edema seen in critically
ill patients and thought to be due to increased capillary permeability.
Pulmonary edema may cause consolidation if severe.
Chronic Consolidation
Adenocarcinoma, previously bronchioloalveolar carcinoma
Lymphoma.
Organizing pneumonia, which is a nonspecific response to injury characterized by granulation polyps
which fill the distal airways, producing peripheral rounded and nodular consolidation.
Chronic eosinophilic pneumonia, an inflammatory process characterized by eosinophils causing alveolar
filling in an upper-lobe distribution.
Acute Ground Glass
Pulmonary edema, which is usually central or dependent.
Pneumonia. Unlike consolidation, ground glass is more commonly seen in atypical pneumonia such as
viral or Pneumocystis jiroveci pneumonia.
Pulmonary hemorrhage, seen as pure ground glass in acute phase, but subacute phase shows peripheral
sparing and crazy paving.
Adult respiratory distress syndrome (ARDS).
Chronic Groundless
Lung adenocarcinoma, which can be focal or multifocal.
Organizing pneumonia, typically presenting as rounded, peripheral opacities.
Chronic eosinophilic pneumonia, usually with an upper-lobe predominance.
Interstitial lung disease, including desquamative interstitial pneumonia (DIP), nonspecific interstitial
pneumonia (NSIP), and hypersensitivity pneumonitis (HP).
Hypersensitivity pneumonitis (HP) is a type III hypersensitivity reaction to inhaled organic antigens. In
the subacute phase there is ground glass, centrilobular nodules, and mosaic attenuation.
Peripheral Consolidation or groundless
Organizing pneumonia.
Chronic eosinophilic pneumonia, typically with an upper lobe predominance.
Pulmonary infarction.
Interlobular septal thickening
Pulmonary edema.
Lymphangiti s carcinomatosis.
Nodular, irregular or asymmetric septal thickening
Lymphangiti c carcinomatosis is tumor spread through the lymphatics.
Sarcoidosis rarely causes septal thickening.
Crazy Paving
Pulmonary edema, by far the most common cause.
Pulmonary hemorrhage.
Acute respiratory distress syndrome.
Pulmonary alveolar proteinosis (PAP), an idiopathic disease characterized by alveolar filling by a
proteinaceous substance. PAP is almost always seen with a crazy paving pattern.
Pneumocystis jiroveci pneumonia.
Adenocarcinoma, uncommon cause
Lipoid pneumonia, an infl ammatory pneumonia caused by reacti on to aspirated lipids, uncommon cause.
Centrilobular Nodules
The most common inflammatory cause of centrilobular nodules is hypersensitivity
pneumoniti s (HP), an exposure-related lung disease.
HP is a type III hypersensitivity reaction to an inhaled organic antigen. The acute or subacute
presentation of HP is primarily characterized by centrilobular nodules.
Pulmonary capillary hemangiomatosis is a vascular pathology characterized by abnormal capillary
proliferation leading to pulmonary hypertension.
Viral pneumonias.
Aspiration is dependent.
Metastatic calcification most commonly occurs in the lung apices, typically in patients with renal failure.
Perilymphatic nodules
Sarcoidosis.
Pneumoconioses (silicosis and coal workers’ pneumoconiosis) are reactions to inorganic dust inhalation.
The imaging may look identical to sarcoidosis with perilymphatic nodules, but there is usually a history of
exposure (e.g., a sandblaster who develops silicosis).
Lymphangitic carcinomatosis.
Randomly distributed nodules
Hematogenous metastases.
Disseminated mycobacteria.
Disseminated fungal infection.
A miliary pattern is innumerable tiny random nodules the size of millet seeds.
Tree in bud nodularity
Mycobacterium tuberculosis and atypical mycobacteria.
Viral pneumonia.
Aspiration pneumonia.
Rarely, lymphangitic carcinomatosis and vascular abnormalities (endovascular metastases and
pulmonary arterial aneurysms).
Solitary cavitary lesion
Solitary cavitary lesion is most likely cancer or infection.
Primary bronchogenic carcinoma. While both squamous cell and adenocarcinoma can cavitate,
squamous cell cavitates more frequently. Small cell carcinoma is never known to cavitate.
Tuberculosis classically produces an upper-lobe cavitary consolidati on.
Fungal pneumonia.
Cavitary bacterial pneumonia.
Multiple cavitary lesions
Septic emboli, typically peripheral.
Vasculitis, including granulomatosis with polyangiiti s (GPA).
Metastases, classically squamous cell carcinoma but any metastatic lesion can cavitate.
multiple lung
cysts includes:
Lymphangioleiomyomatosis (LAM), a diffuse cystic lung disease due to smooth muscle proliferation of
the distal airways. LAM causes uniformly distributed, thin-walled cysts in a diffuse distribution. It may be
associated with chylous effusion, as demonstrated in the above right case.
Pulmonary Langerhans cell histiocytosis, which features irregular cysts and nodules predominantly in
the upper lungs.
Lymphoid interstitial pneumonia (LIP), a rare disease usually associated with Sjögren syndrome and
characterized by lymphocytic infiltrate and multiple cysts.
Amyloid which appears similar to LIP.
Birt-Hogg-Dube syndrome which is an autosomal dominant genetic disorder characterized by renal
tumors (most commonly chromophobe renal carcinoma and renal oncocytoma), and renal and
pulmonary cysts.
Spontaneous pneumothoraxes can occur as a sequela of pulmonary cysts.
Pneumocystis jiroveci pneumonia, which features cysts in late-stage disease.
single cyst includes:
Bulla. A bulla is an air-filled emphysematous space measuring >1 cm. A giant bulla occupies at least 30%
of the volume of the thorax.
Bleb. A bleb is an air-filled cystic structure contiguous with the pleura measuring <1 cm. Rupture of a
bleb is the most common cause of spontaneous pneumothorax.
Pneumatocele, which is an air-filled space caused by prior lung trauma or infection.
basal-predominant fibrotic change includes:
Usual interstitial pneumonia (UIP) pattern. Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome of
progressive pulmonary fibrosis of unknown etiology and is the most common cause of basilar fibrosis. It
almost always features basilar honeycombing.
Other causes of UIP pattern, including rheumatoid arthritis and asbestosis.
Nonspecific interstitial pneumonia (NSIP) is a lung response to injury commonly associated with collagen
vascular disease and drug reaction. NSIP typically produces peribronchial reticulation and traction
bronchiectasis. Ground glass may be present.
Upper lobe fibrosis
Although IPF is the most common cause of pulmonary fibrosis, fibrosis primarily affecting
the upper lobes is typically caused by an alternative diagnosis, such as:
End-stage sarcoidosis. Sarcoidosis is a disease that primarily affects the upper lobes. The late stage of
sarcoidosis leads to upper-lobe predominant fibrosis.
Chronic hypersensitivity pneumonitis.
End-stage silicosis. The late stage of silicosis may lead to fibrosis with an upper lobe predominance.
5 groups of PHTN
Group 1: Pulmonary arterial hypertension (PAH).
Primary pulmonary hypertension (PPH) may be idiopathic or familial.
Congenital left-to-right shunts, such as atrial septal defect (ASD) and ventricular septal defect (VSD), may
cause PAH and shunt reversal (Eisenmenger syndrome).
Group 1 ̍: Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH).
PAH may be caused by pulmonary venous or capillary involvement.
Group 2: Pulmonary venous hypertension.
Left-sided heart disease (left atrial, left ventricular, or mitral/aortic valve disease may cause elevated
pulmonary venous pressure in chronic disease).
Group 3: Pulmonary hypertension associated with chronic hypoxemia.
COPD, interstitial lung disease, and sleep apnea can cause pulmonary hypertension in chronic disease.
Group 4: Pulmonary hypertension due to chronic thromboembolic disease.
Group 5: Pulmonary hypertension due to miscellaneous disorders.
Sarcoidosis is a rare cause of pulmonary hypertension.
Compression of pulmonary vessels, which can be due to neoplasm, fibrosing mediastinitis, etc., may cause
pulmonary hypertension.
Usual interstitial pneumonia
(UIP)
Basilar subpleural reticulation with
honeycombing
Idiopathic pulmonary fibrosis (IPF)
Rheumatoid arthritis
Asbestosis
Drug toxicity
Nonspecific interstitial pneumonia
(NSIP)
Scleroderma
Dermatomyositis
Mixed connective tissue disease
Drug toxicity
Peribronchial reticulation, traction
bronchiectasis, +/- ground glass opacities
Organizing pneumonia
Cryptogenic organizing pneumonia (COP) –
idiopathic
Drug toxicity
Connective tissue disorders, particularly SLE
and dermatomyositis
Peripheral or peribronchial ground glass or
consolidative opacities
Respiratory bronchiolitis (RB)
Smoking-related spectrum Upper lobe centrilobular nodules
Diffuse alveolar damage (DAD)
Acute interstitial pneumonia (AIP)
Acute respiratory distress syndrome (ARDS)
Transfusion-related acute lung injury (TRALI)
Diffuse airspace disease
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Paediatrics55
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Neurology1
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Differentials Chest36
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Hot Seat25
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Differentials GU21
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Differential GI46
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Differentials Neuro0
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Differentials Spine14
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Differentials Paediatrics1
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Differentials Neuro28
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Differentials Nukes1
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Differentials Gynae1
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Differentials Breast1
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Differentials Cardiac1
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Differentials Head and Neck16
