A splenic mass was found in an asymptomatic 76-year-old woman who had been treated with steroids for autoimmune hepatitis. The lesion was found to be hyperechoic on ultrasound examination, hypovascular on angiography, low attenuating on postcontrast computed tomography, isointense to splenic parenchyma on precontrast T1- and T2-weighted images, and showed inhomogeneous enhancement on gadolinium-enhanced T1-weighted images. Splenic peliosis should be considered when diagnosing tumorlike conditions of the spleen because of its potential to cause splenic rupture.