Metanephric stromal tumor arising in a patient with neurofibromatosis type 1 syndrome.

Metanephric stromal tumor (MST) is a recently recognized benign renal stromal tumor. MST is thought to be part of a spectrum of benign metanephric renal lesions, which also includes the epithelial lesion metanephric adenoma and the mixed stromal-epithelial lesion metanephric adenofibroma. Metanephric lesions may represent hyperdifferentiated counterparts to Wilms' tumor (WT). MST characteristically shows renovascular angiodysplasia and juxtaglomerular (JG) cell hyperplasia. This is remarkably similar to the renal pathology described in neurofibromatosis-1 (NF-1) syndrome, a condition which is also associated with WT. Here, we report the first case of MST arising in a patient with NF-1. The patient presented with hypertension, and the MST was associated with florid angiodysplasia and JG cell hyperplasia. This case tightens the link between NF-1, WT, and MST.