PMC9341370_01
A - CEMRI with MR urography shows polypoidal, heterogeneous mass over the anterosuperior aspect of the urinary bladder wall. The mass with both endophytic (arrow head) and exophytic (arrow) growth is seen; B, C, and D are photomicrographs of the bladder tumor; B and C - Pretherapy cystoscopy guided biopsy showing triphasic component comprising blastemal (B; H&E, 200X), and epithelial and mesenchymal elements (C; H&E, 200X); D - The blastemal component positive for WT1 immunostain (200X).
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The contrast-enhanced Magnetic Resonance Imaging (CEMRI) with MR urography revealed a polypoidal, heterogeneous mass over the anterosuperior aspect of the urinary bladder wall (Figure 1A). The blastemal component was placed randomly in a nesting pattern and was composed of primitive small round-to-oval blue cells with hyperchromatic nuclei, inconspicuous nucleoli, and scanty cytoplasm (Figure 1B). The small tubules were lined by cuboidal to columnar cells with hyperchromatic nuclei (Figure 1C). WT1 immunostain highlighted the blastemal and epithelial components (Figure 1D).
A - The partial cystectomy specimen reveals exophytic polypoidal growth; B - The cut surface shows both endophytic and exophytic growth with grey white and firm in appearance. The endophytic component is surrounded by the cystic space containing gel-like material.
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Following chemotherapy, the partial cystectomy showed an exophytic, polypoidal mass (Figure 2A). On serial slicing, the cut surface also depicted the endophytic component measuring 1.5x1.5x1 cm protruding into the cystic space formed around it (Figure 2B).
Photomicrographs of the partial cystectomy specimen showing: A - a polypoidal mass arising within the lumen. Bladder wall with detrusor muscle can be appreciated (right) (H&E, 40X); B - Biphasic component comprising of glomeruli, tubules, and smooth muscle fibers (H&E, 200X); C - Heterologous mucinous epithelium (H&E, 200X); D - Adipocytic and skeletal muscle differentiation (H&E, 200X).
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Microscopically, the polypoidal mass was well-demarcated from the surrounding native bladder parenchyma by the fibrous pseudocapsule (Figure 3A). The epithelial component is comprised of primitive glomerular and tubular structures (Figure 3B). Occasionally, they showed squamous and mucinous differentiation (Figure 3C). The stroma contained smooth muscle, fibroblasts, skeletal muscle, adipose tissue, ganglion cells, and occasional lymphoid aggregates (Figure 3D) with areas of myxoid and edematous change.