Fig. 2

Alveolar proteinosis. a Chest radiograph showed a reticular pattern that was most pronounced in the central parts of the lungs. There was also a decrease in the lung translucency centrally in both lungs. Heart and central vessels were normal. There was no pleural effusion. b On CT, a patchy distribution of a crazy-paving pattern was visible. The lines corresponded to a deposition of material within the airspaces at the borders of the acini (1) in the secondary pulmonary lobules, but also along the interlobular (2) and intralobular septa (3): the periacinar pattern. c Radiological-histopathological correlation. Histopathological evaluation of a specimen out of the right lung showed amorphous eosinophilic material in the alveoli (*) positive on periodic acid Schiff (PAS) staining. This material corresponded to deficient surfactant. Filling of the alveoli (*) was responsible for the ground-glass appearance on CT. When the airspaces adjacent to the inter- and intralobular septa (black arrow) and to the alveolar walls filled, the periacinar pattern became visible