Atypical mesoblastic nephroma. A potentially malignant variant of congenital mesoblastic nephroma. Review of literature & report of four cases.

Atypical Mesoblastic Nephroma (AMN) is a rare infantile renal tumour which may behave aggressively, in contrast to conventional Mesoblastic nephroma. During a 10 year period we encountered four cases of AMN. The mean age of presentation was three months. Size varied from 9-18 cms. All were soft and fleshy with a weight varying from 290-1200 gms. Three cases revealed cystic changes. Hemorrhage and necrosis was seen in all four cases. One case had associated Nephroblastomatosis Complex. The capsule and ureter were involved in one case each. Two of the four patients died of distant metastasis. Thus a close periodic follow up by non-invasive imaging techniques is indicated for early detection of recurrence and or metastasis in cases of AMN.