Congenital mesoblastic nephroma, nephrocalcinosis, and hypertrophic pyloric stenosis.

A cellular variant of congenital mesoblastic nephroma (CMN) occurring in a newborn is presented. Coincidental findings were congenital hypertrophic pyloric stenosis (CHPS) and nephrocalcinotic hypercalcemia that reverted after nephrectomy. As of the day of writing, this multiple association has not been reported. The authors believe that both CMN and CHPS could be interpreted as fibroblastic proliferative-related entities. Transient hypercalcemia seems to be a paraneoplastic phenomenon.