17] Renal neoplasms are thus classified into renal cell (oncocytoma, papillary adenoma), metanephric
, mesenchymal (AML, hemangioma, lymphangioma, leiomyoma, renomedullary interstitial cell tumor), and mixed epithelial and mesenchymal (mixed epithelial and stromal tumor, cystic nephroma) tumors (Table 1).
Of note, all metanephric
tumors, which are characterized by an "embryonic" phenotype, display a level of PAX2 expression significantly beyond the already strong staining of other RCC types such as clear cell or papillary RCC, reflecting the pronounced PAX2 expressions during renal embryogenesis.
The kidney derives from the nephric ridge of the intermediate mesoderm where the pro-nephric duct elongates to form the Wolffian duct, which in turn gives rise to the ureteric bud and sets the stage for condensation of metanephric
mesenchyme and mesynchemal-to-epithelial cell transition.
CD57 is a useful marker for the diagnosis of metanephric
apoptosis and abnormal kidney development in bcl-2-deficient mice.
4] The embryological anomaly is from premature division of the metanephric
bud; the number of kidneys probably reflects the number of abnormal divisions of the progenitor cells.
Solid mixed epithelial and stromal tumors also need to be distinguished from mesoblastic nephroma and metanephric
2 translocation carcinoma, metanephric
adenoma, collecting duct carcinoma, mucinous tubular and spindle cell carcinoma, and chromophobe RCC.
The positivity for cytokeratin 7, cytokeratin 8/18, and vimentin is useful in differentiating papillary RCC from other primary renal neoplasms, including metanephric
adenoma, chromophobe RCC, oncocytoma, and urothelial cell carcinoma of the renal pelvis.
Renal cystic diseases (RCDs) and congenital abnormalities of the kidney and urinary tract (CAKUT) comprise a group of metanephric
and ampullary bud misadventures and acquired lesions that have captured the interest and challenged the imagination of physicians for centuries.
3-11) These tumors have been published under the following names in the literature: leiomyomatous renal hamartomas, congenital mesoblastic nephroma in an adult, cystic hamartoma of renal pelvis, solitary multilocular cysts of the kidney, multilocular renal cyst with mullerian-like stroma, and adult metanephric
Dysplastic changes are defined as altered metanephric
differentiation during embryogenesis, leading to abnormal kidney.