PMC10293613_01
Macroscopic appearance of the gout tophus removed from the right elbow of a 73-year-old man.
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F1
Histopathological examination of the removed gout tophus from the right elbow demonstrated a fibrofatty mass measuring 70 x 46 x 22 mm (Figure 1).
On grossing the sample amorphous deposits of white material were seen predominantly within the reticular dermal area and extended down to the subcutaneous fat.
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F2
Macroscopically on slicing the tophus, areas of amorphous crystalloid material were seen and identified predominantly within the reticular dermal area (Figure 2).
(A): H&E staining of the microscopic appearance of the dermal amorphous eosinophilic deposits. Mag x20. (B): H&E staining of the microscopic appearance of the crystalloid structures. Mag x20. (C): H&E staining demonstrating the appearance of cholesterol clefts. Mag x40.
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F3
Within the reticular and subcutaneous tissue there were areas of amorphous pale eosinophilic material with associated crystalloid structures (Figures 3A, B) displaying a feathery appearance with characteristic needle-shaped spaces (Cholesterol clefts) (Figure 3C).
(A): H&E staining of the inflammatory infiltrate composed of foreign body multi-nucleated giant cells (black arrow). Mag x40. (B): H&E staining of the inflammatory infiltrate composed of Touton type multi-nucleated giant cells (black arrow) Mag x40.
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F4
Touton types) (Figures 4A, B arrowed), plus the presence of fibrosis. The amorphous material extended to the papillary dermis and special stains for amyloid were conducted which included Congo Red (CR) (Figure 5) and Thioflavine-T (Thio-T) (Figure 6).
Congo Red (CR) staining of the amorphous AA amyloid deposits within the reticular dermal area Mag x40.
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F5
Touton types) (Figures 4A, B arrowed), plus the presence of fibrosis. The amorphous material extended to the papillary dermis and special stains for amyloid were conducted which included Congo Red (CR) (Figure 5) and Thioflavine-T (Thio-T) (Figure 6).
Fluorescent microscopy of Thioflavin-T (Thio-T) staining of the AA amyloid deposits found within the dermal area. Mag x40.
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F6
Touton types) (Figures 4A, B arrowed), plus the presence of fibrosis. The amorphous material extended to the papillary dermis and special stains for amyloid were conducted which included Congo Red (CR) (Figure 5) and Thioflavine-T (Thio-T) (Figure 6).
Congo Red (CR) staining with cross polarisers demonstrating the Uric acid crystalloid structures. Mag x30.
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F7
Using cross-polarized light the crystalloid structures (Figure 7) within the amorphous material located within the papillary and reticular dermal areas exhibited birefringence in the CR-stained sections and was positive with Thio T confirming the presence of amyloid.