Infantile scrotal pyocele simulating missed testicular torsion on sonography

We present the case of a neonate with idiopathic infantile pyocele. Scrotal sonography revealed a complex fluid collection within the left scrotal sac containing septations and a fluid-fluid level. The dependent region of the collection had moderate echogenicity, the slightly hypoechoic testis was not well defined, and the scrotal wall was thickened. Color Doppler sonography revealed mild hypervascularity in the thickened scrotal wall but no vascularity inside the testis. The sonographic findings suggested missed testicular torsion, but surgery revealed a pyocele, for which no source was identified. Radiologists should be aware that idiopathic infantile pyocele can mimic the Doppler sonographic findings in missed testicular torsion.