PMC7691173_01
Chest computed tomography (CT) scan. (a, b) Images at the time of hospitalization. Non-segmental peripheral and peri-bronchovascular consolidation with air-bronchogram is shown at the middle lobe of the right lung and upper lobe of the left lung, which corresponds to the OP pattern. (c, d) Images when steroid treatment started (on the 10th day after hospitalization). Consolidations were expanded, and bilateral pleural effusion associated with malnutrition was also observed. (e, f) Images thirteen days after steroid treatment started (on the 23rd day after hospitalization and 13th day after steroid pulse therapy). Improvement of lesions was apparent. In addition to the images, data on his daily body weight and serum albumin level were presented. Emergence and disappearance of pleural effusion on the timeline of his clinical course corresponded to steroid treatment and data on serum albumin level and body weight.
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The features were considered to correspond to OP pattern (Fig. 1a and b); hence, the patient was hospitalized. Then, he presented with bilateral pleural effusion (Fig. 1c and d); thus, thoracentesis was performed. On CT imaging, consolidation improved significantly and bilateral pleural effusion disappeared on the 13th day after the initiation of steroid pulse therapy (45 days after the initial presentation of fever) (Fig. 1e and f).
Transbronchial lung biopsy from the middle lobe showed alveolitis with an intra-alveolar organization (i.e., organizing pneumonia with polypoid fibrosis) and mucus plugs (a): Alcian blue staining,x4 magnification; (b): hematoxylin-eosin staining, x 20; (c): Elastica van Gieson staining, x20. Renal biopsy showing focal cellular crescent formation in one glomerulus (d): hematoxylin-eosin staining (H&E), x 10; (e): periodic acid methenamine silver staining, x 40. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
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Histopathological examination of the transbronchial biopsy revealed OP lesion with separately observed mucus plug (Fig. 2a,b,c); however, there was no evidence of granuloma formation, extensive eosinophilic infiltration, alveolar hemorrhage, and vasculitis. The histopathological examination of the renal biopsy showed segmental collapse, inflammatory cell infiltration, and crescent formation in one glomerulus, suggesting underlying AAV (Fig. 2d and e), and the patient was diagnosed with MPO-ANCA positive AAV.