PMC8046523_01
Contrast enhanced CT images of the tumour. (a) An axial section showing the left renal tumour showing the aneurysm (asterisk). The tumour involves the entire kidney except a thin rim of normally enhancing renal tissue at the upper outer region. (b) CT renal angiogram showing multiple feeding arteries and the aneurysm (asterisk). The vasculature of the extrarenal cystic nodule (double asterisks) is also seen inferior to the aneurysm.
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fig1
Additionally, there was an aneurysm of 4.5 x 3.5 cm inside the tumor, the feeding artery of which could also be identified (Figure 1).
Macroscopic appearance of the tumour. (a) An immediate postoperative image of the specimen showing the left kidney, extrarenal tumor nodule (asterisk) and the vessels supplying it (+). (b) The external appearance of the specimen after formalin fixation demonstrating the separate tumor nodule (asterisk). (c) Cut surface showing the tumour involving the entire kidney sparing a thin rim of normal kidney tissue (+) and the aneurysm filled with a blood clot (asterisk).
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It measured 5 x 4.5 x 4 cm and had distinct blood supply (Figure 2). There was a blood-filled cavity in the posteromedial aspect of the kidney measuring 4.5 x 3.8 x 3.5 cm which is compatible with the radiologically identified aneurysm (Figure 2).
Microscopic appearance of the tumour. (a) Closely packed nests comprising a dual population of cells:H&E 40x. (b) High-power view showing nests of large polygonal cells with clear cytoplasm, surrounded by a thin capillary network. The admixed second population of small cells are forming rosettes around deeply eosinophilic basement membrane like material:H&E 400x. (c) Positive immune-staining for Melan-A. (d) Negative staining for Vimentin.
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The periphery of the nests had large polygonal cells with central rounded nuclei and abundant clear cytoplasm (Figure 3).
The extrarenal tumor nodule. (a) A cut section showing multilocular cystic structure with thin fibrous septae. (b) Microscopy showing thin-walled cysts lined by a dual population of cells, similar to the main tumour:H&E 200x.
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fig4
The immunohistochemical staining pattern of it was also identical that of the primary tumour, i.e., diffuse cytoplasmic positivity for Melan-A and negative staining for Vimentin, HMB 45, and CD 117 (Figure 4).