[Congenital mesoblastic nephroma. Study of five cases and review of the literature (author's transl)].

Mesoblastic nephroma (individualized by Bolande in 1967) is a congenital renal tumor sometimes locally and regionally aggressive but never giving metastases, in contrast with nephroblastoma. It almost always occurs in the newborn. Therefore, every renal tumor discovered before twelve months must evoke mesoblastic nephroma. No preoperative adjuvant treatment must be used in infants under six months old. Considering five personal observations and review of literature, the authors expose the main etiologic and clinical characteristics of the disease, the gross and microscopic features which allow its diagnosis and the histogenetic theories of this curious lesion, probably border-line between neoplasias and dysplasias of renal parenchyma.