Desmoplastic small round cell tumor of the kidney with unusual imaging features.

Desmoplastic small round cell tumor (DSRCT) is a rare, high-grade sarcoma seen in children and young adults. DSRCT of the kidney is extremely uncommon, but has been described in both pediatric and adult populations. Here we present an unusual manifestation of renal DSRCT in a boy whose imaging studies revealed a well-circumscribed mass confined to the urinary collecting system, rather than a large aggressive-appearing mass typically associated with DSRCT, which highlights the varied clinical and imaging features of this disease.