Crazy paving


A non-specific radiographic pattern with ground glass opacities, which suggest alveolar filling, and interlobular septal thickening, which suggests an interstitial process.

It is classically associated with pulmonary alveolar proteinosis, the pattern is nonspecific and can be present in diverse processes: bronchoalveolar carcinoma, primary pulmonary lymphoma, sarcoidosis, lipoid pneumonia, acute respiratory distress syndrome, pulmonary edema, diffuse alveolar hemorrhage, and infections including P. jirovecii pneumonia.

Common finding at thin-section computed tomography (CT) of the lungs.

Consists of scattered or diffuse ground-glass attenuation with superimposed interlobular septal thickening and intralobular lines.

Causes include: infectious, neoplastic, idiopathic, inhalational, and sanguineous disorders.

Disorders that can cause the crazy-paving pattern include Pneumocystis carinii pneumonia, mucinous bronchioloalveolar carcinoma, pulmonary alveolar proteinosis, sarcoidosis, nonspecific interstitial pneumonia, organizing pneumonia, exogenous lipoid pneumonia, adult respiratory distress syndrome, and pulmonary hemorrhage syndromes.

Patterns are frequently indistinguishable at radiologic evaluation, differences in the location of the characteristic attenuation in the lungs, as well as the presence of additional radiologic findings, the patient’s history, and the clinical presentation, can often be useful in suggesting the appropriate diagnosis.

It was initially described in cases of alveolar proteinosis, this pattern has subsequently been reported in a variety of infectious, neoplastic, idiopathic, inhalational, and sanguineous disorders of the lung.

Pneumocystis cariniipneumonia is a common pulmonary infection in the severely immunocompromised patient?

Pneumocystis carinii symptom include dry cough, dyspnea, and low-grade fever.

In Pneumocystis carinii chest radiographs are normal in up to 18% of patients, and the typical radiographic manifestations are bilateral, perihilar reticular and poorly defined ground-glass opacities, which often progress to alveolar consolidation in 3–4 days.

High-resolution CT usually reveals scattered ground-glass attenuation that can be associated with interlobular septal thickening.

The features contributing to the ground-glass attenuation appearance include the foamy nature of the alveolar exudates and thickening of the alveolar walls by edema and cellular infiltrates.

Bronchioloalveolar carcinoma is classified into mucinous and nonmucinous subgroups.

Mucinous bronchioloalveolar carcinoma, consists of mucin-producing columnar cells with moderate nuclear atypia.

Bronchioloalveolar carcinoma is characterized by a lepidic growth pattern through the airways and air spaces with preservation of the lung architecture.

Bronchorrhea, the expectoration of copious quantities of sputum, is an uncommon but characteristic clinical feature.

Radiographic findings include ill-defined consolidation or ground-glass opacities that occur in a focal or multilobar distribution.

Lymphadenopathy and pleural effusion occur occasionally.

High-resolution CT manifestations are numerous and include alveolar consolidation and ground-glass attenuation, which occasionally manifest as a crazy-paving pattern.

The ground-glass attenuation reflects the low-density intraalveolar material of glycoprotein, whereas the superimposed reticular attenuation is due to infiltration of the interstitium by inflammatory or tumor cells.

Pulmonary alveolar proteinosis manifests as filling of the alveoli by a proteinaceous material that is positive at periodic acid–Schiff staining and rich in lipid, in association with an inflammatory response in the adjacent interstitium.

Pulmonary alveolar proteinosis is most common in adults between 20 and 50 years of age.

In pulmonary alveolar proteinosis dyspnea and nonproductive cough are the most common symptoms, while pleuritic chest pain, malaise, and low-grade fever are less common.

In pulmonary alveolar proteinosis classic radiographic finding is bilateral, symmetric alveolar consolidation or ground-glass opacity, particularly in a perihilar or hilar distribution resembling pulmonary edema.

High-resolution CT typically shows diffuse ground-glass attenuation with superimposed intra- and interlobular septal thickening, often in polygonal shapes representing the secondary pulmonary lobule.

The diagnosis of pulmonary alveolar proteinosis is established with bronchoalveolar lavage.

Sarcoidosis is a systemic entity characterized by the development of noncaseating granulomatous inflammation, and parenchymal findings include irregular thickening of the bronchovascular bundles and small nodules along vessels, while alveolar sarcoidosis can manifest as ground-glass attenuation and crazy-paving attenuation.

Nonspecific interstitial pneumonia describes interstitial inflammation and fibrosis, but does not fulfill clinicopathologic criteria for usual interstitial pneumonia, desquamative interstitial pneumonia, or acute interstitial pneumonia.

Nonspecific interstitial pneumonia clinical presentation is similar to that of interstitial pulmonary fibrosis, although it is associated with a much better prognosis

Chest radiographic findings include bilateral pulmonary opacities, mainly in the middle and lower zones.

The most common CT abnormality in nonspecific interstitial pneumonia seen in 80% of cases is ground-glass attenuation.

In Nonspecific interstitial pneumonia the ground-glass attenuation is usually bilateral and symmetric with a tendency to subpleural and basal predominance.

Honeycombing is typically absent in Nonspecific interstitial pneumonia, and this characteristic can be useful in narrowing the differential diagnosis with the other interstitial pneumonias.

Organizing pneumonia is a chronic inflammatory process characterized by granulation tissue in the lumina of distal small airways, often extending into the alveolar spaces, associated with intraalveolar foamy macrophages and an interstitial cellular response.

Most cases of organizing pneumonia are idiopathic, but are associated with collagen-vascular diseases such as rheumatoid arthritis, mixed connective-tissue disease, infection, and toxic effects of drugs-bleomycin, methotrexate, cyclophosphamide, gold salts, topotecan, and amiodarone.

Patients with organizing pneumonia usually present with cough, dyspnea, fever of several weeks duration, and leukocytosis.

Steroid therapy is used for organizing pneumonia.

Chest radiographs and CT frequently show scattered and asymmetric consolidation bilaterally, and predominantly peripherally.

The crazy-paving pattern is uncommon finding.

Lipoid pneumonia is a pulmonary disorder resulting from chronic aspiration or inhalation of animal, vegetable, or petroleum-based oils or fats.

Lipoid pneumonia reveals intraalveolar macrophages containing abundant cytoplasmic lipoproteinaceous material within normal-appearing alveoli.

Exogenous lipoid pneumonia can also manifest as geographic ground-glass attenuation associated with interlobular septal thickening within areas of ground-glass attenuation, reflecting intraalveolar and interstitial accumulation of lipid-laden macrophages and hyperplasia of type II pneumocytes in the alveolar lining.

Adult respiratory distress syndrome is a form of pulmonary edema characterized by refractory hypoxemia and respiratory distress.

Adult respiratory distress syndrome has numerous causes including: shock, contusion, infection, sepsis, aspiration, drug abuse, and inhalation of noxious substances.

Adult respiratory distress syndrome diagnosis based on impaired diffusion capacity, reduced compliance of the lung, and typical radiologic findings.

Chest x-rays typically show bilateral homogeneous pulmonary opacities.

High-resolution CT reveals bilateral consolidation and ground-glass attenuation, such as reticular and linear attenuation, architectural distortion, consolidation with bronchiectasis, and honeycombing may be seen.

Pulmonary hemorrhage syndromes include a wide spectrum of diseases: idiopathic pulmonary hemosiderosis, Wegener granulomatosis, Churg-Strauss syndrome, Goodpasture syndrome, collagen-vascular diseases, drug-induced coagulopathy, and hemorrhage associated with malignancy.

Chest radiographic and CT manifestations are symmetric acinar and ground-glass opacities or attenuation and the crazy-paving pattern.

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