Atypical congenital mesoblastic nephroma presenting in the perinatal period.

Congenital mesoblastic nephroma (CMN) is a rare tumour of infancy having an overall good prognosis. The less common, atypical CMNs have cellular elements in them and tend to have an unpredictable course. Occurrence in the perinatal period may further change the outcome. By reporting three patients presenting in the perinatal period with atypical CMN, an attempt is made in this paper to characterize the clinical behaviour of these variant tumours. Though one of our patients had an uneventful course, the other two had several complications including polyhydramnios, prematurity, hypertension, haemodynamic instability and tumour spillage. The course was complicated by recurrence in the latter two and refractoriness to chemotherapy and death in one. That the atypical subset of CMNs occurring in the perinatal period can have a stormy course is well illustrated by this report. Possible prognostic factors are evaluated and the sparse reports of similar cases in the literature are reviewed and compared.