Massive hydronephrosis mimicking theca lutein cysts in association with partial hydatidiform mole.

We present an unusual case of partial hydatidiform mole in which extensive, multiple cystic structures encompassing the entire right abdomen and pelvis, initially thought to represent theca lutein cysts, were subsequently shown to consist of massive unilateral right hydronephrosis. Percutaneous nephrostomy decompression bypassing the ureteropelvic obstruction revealed functional renal parenchyma.