PMC5137237_01
(a) Abdominopelvic computed tomography image shows marked hydronephrosis (blue arrow) affecting the right kidney without an obvious mass in the upper urinary tract. (b) Positron emission tomography/computed tomography revealed multiple high signal intensities (C7-T4 spinal vertebrae, para-aortic lymph nodes, red arrows) suggesting metastatic carcinoma from an unknown primary
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F1
Abdominopelvic computerized tomography (CT) revealed postrenal obstructive hydronephrosis without a definitive mass in the upper urinary tract [Figure 1a], which suggested renal/ureteral tuberculosis or an unknown masked metastatic carcinoma. Positron emission tomography/CT revealed multiple high-intensity signals in the C7 to T4 spinal vertebrae and intra-abdominal para-aortic lymph nodes, suggesting metastatic malignancy of unknown origin (MUO) [Figure 1b].
(a) Urine cytology preparation containing clusters of atypical epithelial cells in a background of umbrella cells (blue arrow) and inflammatory cells. The atypical cells are arranged in three-dimensional clusters, resembling an adenocarcinoma (Inset) (Pap, x400). (b) The umbrella cells only express cytokeratin 20 antigen (p53/CK20 double immunostaining, x400). (c) The atypical cells demonstrate a distinct pattern of double staining: red nuclei (p53) and brown cytoplasm (cytokeratin 20) (p53/CK20 double immunostaining, x400)
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Examination of a cytological preparation from a urine specimen found clusters of large atypical cells with abundant cytoplasm and prominent nucleoli, suggesting malignancy, type undetermined [Figure 2a]. Subsequent double immunostaining for CK20/P53 expression of a cytological preparation from the same urine sample found CK20-positive umbrella cells [Figure 2b] and CK20-positive/p53-positive atypical cells, suggestive of UC [Figure 2c].
(a) Nephroureterectomy specimen showing cystically dilated renal pelvis and ill-defined mass (2.5 cm) in the lower renal pelvis (red circle). (b) The scanning power view shows relatively intact urothelium and underlying atrophic renal parenchyma (H and E, x10) Papillary proliferation of urothelium and underlying micropapillary nests in lacunar spaces suggest micropapillary urothelial carcinoma (Inset) (H and E, x100). (c) Tumor cells are seen infiltrating the perirenal fat tissue (blue arrow) (pT4 disease) (H and E, x10)
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The operative findings included an ill-defined infiltrating mass (2.5 cm) in the lower right renal pelvis [Figure 3a]. Histopathological examination found tumor cells that were arranged in micropapillary clusters with frequent lymphovascular invasion [Figure 3b]. The tumor cells infiltrated through the renal parenchyma into perinephric fat tissue, indicating advanced disease (pT4) [Figure 3c].