Color Doppler sonography in evaluation of spermatoceles: the "falling snow" sign.

OBJECTIVE: Doppler sonography is not commonly used in evaluation of cystic lesions with internal echoes. Here we report the use of the mechanical properties of color Doppler sonography to further characterize 3 spermatoceles.

METHODS: Three patients who came to University of California San Francisco Imaging Center with painless unilateral scrotal enlargement were evaluated with sonography and were found to have large spermatoceles. Color Doppler sonography was applied to these spermatoceles, and digital video clips were obtained as the color beam was instituted.

RESULTS: When color Doppler sonography was applied to each spermatocele, the internal echoes moved away from the transducer, resulting in an appearance similar to falling snow.

CONCLUSIONS: The "falling snow" sign can be used to enhance the diagnosis of a spermatocele as well as to evaluate a superficial cystic lesion with echogenic fluid and internal microdebris that is difficult to distinguish from a solid mass.