There is a large well-defined multivesicular cystic mass (13 x 7 x 6 cm) of intramuscular location in the right iliacus muscle composed of numerous cysts of variable sizes of low signal on T1, high signal on T2 and intercystic solid matrix of isosignal to the muscles on T1 and slightly high signal on T2. No enhancement of the cystic wall or the solid matrix on postcontrast sequences.