PMC5925949_01
High Resolution computed tomography at diagnosis showing pattern with interlobular thickening and ground glass opacities, and not a classical crazy paving pattern.
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PMC5925949_01_gr1.jpg
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High resolution computed tomography (HRCT) showed bilateral changes typical for PAP with not a classical crazy paving pattern (Fig. 1).
Light microscopy of the surgical biopsy from the left lung's lingula shows lung parenchyma containing large areas where the alveoli are totally filled with a granular proteinaceous material that is strongly eosinophilic on hematoxylin-and eosin staining (HE). The alveolar walls display diffuse moderate infiltration of lympho-histiocytic cells. The intraalveolar material is also positive with the periodic acid-Schiff stain and diastase-resistant (PAS + D), as well as strongly immunohistochemically positive for surfactant-A protein (S-A) and to a less extent for surfactant-B (not shown), consistent with its derivation from surfactant phospholipids and protein components. Accumulation of surfactant-A is also seen in the hyperplastic pneumocytes covering the alveolar walls and in the intraalveolar macrophages. Cytokeratin staining (CK) highlights the hyperplastic type-II pneumocytes on the alveolar walls and the proteinaceous cell debris of exfoliated pneumocytes in the intraalveolar material. (All figures, 100X).
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A surgical biopsy revealed alveoli filled with a granular proteinaceous material, strongly eosinophilic on hematoxylin-and eosin staining (HE) and positive with the periodic acid-Schiff stain and diastase-resistant (PAS + D), which is considered characteristic for PAP (Fig. 2).