PMC7695879_01
Chest CT findings at the initial examination. Consolidation and heterogeneous ground-glass opacities with multiple cystic lesions are observed mainly in the left lung. The lesions are distributed predominantly in the inner layer of the lung. Areas of mildly low attenuation are observed predominantly in the right upper lobe.
gr1.jpg
PMC7695879_01_gr1.jpg
fig1
Chest computed tomography (CT) scan revealed consolidation and heterogeneous ground-glass opacities with multiple cystic lesions, predominantly in the left lung (Fig. 1).
Histological features of VATS lung. A. Panoramic view showing massive accumulation and infiltration of inflammatory cells with various degree. H&E staining. B. Central basophilic necrosis containing many eosinophils around and surrounded by epithelial cell layer (arrow). H&E staining, x200. C. Tiny intraluminal organizations (arrows) were noted together with inflammatory cells in the airspace and interstitium. Lung structure was preserved. EvG staining, x100.. D. Disruption of epithelial layer (black arrows) and dropout (red arrow) were noted. Immunostaining using AE1/AE3, x. 100. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
gr2.jpg
PMC7695879_01_gr2.jpg
fig2
The degree of inflammation was different among lobules (Fig. 2A). In a higher-magnification image, massive accumulation of macrophages and eosinophils were noted in the airspace and associated with many tiny eosinophilic abscesses containing basophilic necrotic cells (Fig. 2B). Interstitial connective tissue framework assessed by Elastica van Gieson (EvG) staining indicated that majority of lung structure was preserved (Fig. 2C). Various shaped intraluminal organization was also noted (Fig. 2C, arrows) in many areas in addition to cellular accumulation.
Histology and immunostaining of a lung obtained throughout video-assisted thoracoscopic surgery. After immunofluorescence staining for the indicated targets (ii, iv), identical tissue slides were further stained with hematoxylin and eosin (H&E) (i, iii) and identical fields were compared. The open arrowhead in Aii indicates an example of an intact eosinophil containing a large amount of cytoplasmic galectin-10. In contrast, the closed arrowhead in Aii shows an area of granule protein deposition without galectin-10 staining, which indicates cytolytic degranulation. At a higher magnification, galectin-10-positive needle-like Charcot-Leyden crystals (CLCs; closed arrowheads in Aiv) and granular major basic protein (MBP) staining (cell-free granules) are visible. Bi-iv demonstrates the massive formation of a collection of chromatolytic cells with free eosinophilic granules/eosinophil extracellular traps, which stained positively for citrullinated histone 3 (citH3). The biopsy samples were fixed and processed as previously described. DNA was counterstained with Hoechst 33342 (blue). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
gr3.jpg
PMC7695879_01_gr3.jpg
fig3
As shown in Fig. 3Ai and ii, H&E staining revealed an inflamed tissue with few intact eosinophils and significant tissue MBP deposition. A higher-magnification image (Fig. 3Aiii, iv) showed few recognizable eosinophils and the presence of cell-free eosinophilic granules and Charcot-Leyden crystals, some of which had likely been phagocytosed. A substantial numbers of cells exhibited decondensed/disrupted nuclei and abundant cell-free granules with histone hyper-citrullination (Fig. 3Bi-iv).
The patient's clinical course. The patient's peripheral blood eosinophil count tended to decrease during a post-admission follow-up without treatment. Chest CT obtained on day 13 reveal that the extent of the lesions in the left upper lobe has increased. However, the extent of the lesions in the left lower lobe has decreased, and some cysts have become smaller. He was discharged on day 36.
gr4.jpg
PMC7695879_01_gr4.jpg
fig4
To date (approximately 19 months post-discharge), no recurrence has been detected (Fig. 4).