PMC6380127_01
(a) Large slightly H_shaped anterior mediastinal mass, partially capsulated with tags of adipose tissue; the mass had a yellowish brown cut surface and had encased (b) the right RIV and left innominate (LIV), veins, and arch of aorta, and (c) the proximal descending thoracic aorta (DTA) and tracheo_bronchial tree (LB = left bronchus, RB = right bronchus, T = trachea); (d) granulomatous inflammation amidst extensive sclerosis (H and E x 250); and (e) Langhan's giant cells (arrows) accompanied by lymphocytes and few plasma cells (H and E x 400)
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F1
The anterior mediastinum showed a large 9 x 8 x 6 cm slightly H-shaped [Figure 1a], extremely firm to stony hard, partially capsulated mass with a pale yellow to focally congested cut surface. It had encased the superior vena cava and its tributaries, arch of aorta and its branches [Figure 1b], the pulmonary arteries, the trachea, main bronchi, and proximal 4 cm of the descending thoracic aorta [Figure 1c]. The mediastinal mass was essentially composed of densely collagenized fibrous tissue with foci of vascularisation, lymphoplasmacytic infiltrate, occasional aggregates of neutrophils and eosinophils, and scattered granulomatous reaction [Figure 1d and e].
Small vessels showing (a) nonocclusive fresh fibrin thrombus (arrow) and (b) fibrinous and inflammatory obliteration (H and E x 400), (c) coagulative necrosis (H and E x 250), and (d) lightly basophilic intracytoplasmic septate hyphal form (arrow) seen in the giant cell (H and E x 400)
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F2
In many areas, there was abundant perivascular inflammation with focal vasculitis and luminal fibrin thrombi [Figure 2a and b]. The central portion of the mass showed a large area of coagulative necrosis [Figure 2c]. The cytoplasm in some of them contained refractile, slender, and lightly basophilic septate hyphal structures [Figure 2d].
(a) Well_preserved coronal slice showing a circumscribed friable subcortical area (arrow) in the right frontoparietal region, (b) there was prominent perivascular lymphohistiocytic infiltrate (arrows, H and E x 250), (c) the giant cells (arrow), and (d) obliterated vessels and the white matter showed presence of septate hyphal forms (arrows, H and E x 400). Inset shows septate hyphae demonstrated by the Gomori methenamine silver (x400)
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F3
On serial coronal slices, a large well-circumscribed, nodular, firm mass was seen in the right frontoparietal region [Figure 3a]. The histology showed dense perivascular mononuclear inflammation, granulomatous inflammation, and vasculitis with fibrin thrombi; many acute-angle branching septate fungal filaments were seen amidst and within the giant cells [Figure 3a-d]. Gomori methanamine silver stain confirmed the presence of fungal filaments [Figure 3, inset].