Nephrogenic rests (NRs) are abnormally persistent clusters of embryonal cells, representing microscopic dysplasias of the developing kidney.
Clinicopathologic features of nephrogenic rests and nephroblastomatosis.
A competing theory suggests that spindle cells resemble intralobar nephrogenic rests and that these lesions may lie within the pathologic spectrum of Wilms' tumours.
Other diagnoses on the differential for a calcified renal mass in this particular age group include Wilms' tumour, nephrogenic rest, renal cell carcinoma, extra-adrenal neuroblastoma, calcified hematoma and post-infectious (e.
Heterologous differentiation, blastemal elements, nephrogenic rests
favor diagnosis of Wilms tumor.
1,2 Histologically this tumour seems to be related to epithelial Wilms' Tumour and Nephrogenic Rests and in fact these lesions may coexist.
3,12 From the clinical and diagnostic viewpoint the importance of this tumour depends on differentiating it from nephrogenic rests (nodular renal blastema), epithelial Wilms' tumour, solid papillary renal cell carcinoma and metastatic cancers.
3,4,7,9,13 Both nephrogenic rests and Wilms' tumour on microscopy contain a blastema component whereas MA has no primitive blastema.
Metanephric adenoma, nephrogenic rests
, and Wilms' tumor: a histologic and immunophenotypic comparison.
3) The presence of cartilage in mesoblastic nephroma invokes a differential diagnosis of Wilms tumor, but features favoring Wilms tumor over mesoblastic nephroma include the presence of skeletal muscle and blastema, age older than 1 year, bilateral tumors, and nephrogenic rests
With regard to those tumors occurring in the female genital tract, the most plausible histogenetic theory relates to the occurrence of primitive nephrogenic rests