Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Pulmonary Alveolar Proteinosis (PAP)
- Radiologic Findings
- Figure 1. Chest PA shows bilateral widespread and symmetric parenchymal opacities
Figure 2-6. CT scans reveals diffuse widespread ground glass opacities with superimposed smooth interlobular septal thickening giving a typical appearance called "crazy paving pattern”. There is subpleural and equivocal costophrenic recess sparing.

- Brief Review
- Pulmonary alveolar proteinosis (PAP) is a rare respiratory syndrome characterized by the accumulation of surfactant lipoproteins within the alveoli, caused by an impairment of surfactant clearance or abnormal surfactant production, leading to variable impairment of the respiratory function. Diagnosis of PAP is initiated by computed tomography (CT) scan and confirmed by staining of bronchoalveolar lavage fluid (BALF). PAP is classified, according to various pathogenetic mechanisms, as primary, secondary or congenital; primary autoimmune form represents 90% of all PAP cases.
Chest radiography commonly demonstrates diffuse bilateral symmetrical infiltrates in a perihilar distribution, which can progress to confluent infiltrates involving all the five lobes. High-resolution computed tomography (HRCT) of the chest is mandatory to identify the peculiar radiological pattern that is characterized by interlobular septal thickening associated with patchy ground glass, known as “crazy paving”, referring to the polygonal appearance of the secondary pulmonary lobules within interspersed ground-glass attenuation. Areas of consolidation with air bronchograms can be present in addition to the ground-glass opacification. Fibrosis on HRCT at baseline or at follow-up predicts a poor prognosis. Pleural effusion, enlargement of mediastinal lymph nodes and evidence of air trapping are not characteristic, and should lead to alternate or concomitant diagnosis. Pulmonary nodules are also atypical and should be assessed for malignancy or infection. BALF staining is required for the diagnosis of PAP. When performed in a diseased lung area, BALF typically has a milky appearance but might appear abnormal or normal if performed in a healthy zone with a weak amount of lipoproteinaceous material.
Whole-lung lavage is the current gold standard of care of PAP; however, the therapeutic approach is strictly related to the pathogenic form and disease severity, including granulocyte–macrophage colony-stimulating factor augmentation strategies in autoimmune PAP and other promising new treatments.
- Please refer to
Case 198, Case 275, Case 404, Case 496, Case 505, Case 525, Case 624, Case 670, Case 692, Case 818, Case 843, Case 880, Case 883, Case 1033, -
KSTR Symposium 1998 Case 6
,
KSTR Imaging Conference 2006 Summer Case 8
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KSTR Imaging Conference 2009 Spring Case 1
,
KSTR Imaging Conference 2015 Spring Case 9
,
KSTR imaging conference 2017 Spring Case 13,
- References
- 1. Elena Salvaterra, Ilaria Campo.Pulmonary alveolar proteinosis: from classification to therapy. Breathe Jun 2020, 16 (2) 200018; DOI: 10.1183/20734735.0018-2020
- Keywords
- lung, Pulomary Alveolar Proteinosis ,