kidney cancer mesoblastic nephroma mesoblastic nephroma DOID:4772 mesoblastic nephroma (morphologic abnormality) UMLS:C0206628 MONDO:0003130 ICD9:236.99 A solid, unencapsulated tumor of the kidney composed of spindle mesenchymal cells that resemble fibroblasts or muscle cells. The homogeneous mass typically extends into the renal parenchyma and replaces most of the kidney. In most cases, mesoblastic nephroma is benign and occurs in the fetus or newborn, and rarely in the older child or the adult. MEDGEN:64620 EFO:0007365 MESH:D018201 SCTID:307604008