[A case of retroperitoneal capillary malformation examined by contrast-enhanced ultrasonography with perfluorobutane (Sonazoid®)].

A man in his 60s with hyperamylasemia underwent contrast-enhanced computed tomography, which revealed masses in his pelvic cavity on the right side and in the left axilla. Hence, a detailed examination was performed. Upon performing Sonazoid^® (perfluorobutane) contrast-enhanced ultrasound, it was discovered that the right-sided pelvic cavity mass exhibited centripetal contrast-enhancement right from the early stage. Subsequently, the contrast material disappeared from the center and was washed out in the postvascular phase. The mass was suspected to be caused by vascular malformations. The right-sided pelvic cavity mass was excised, and upon histopathological examination, it was detected to be composed of capillary malformations. Thus, it was found that Sonazoid^® contrast-enhanced ultrasound examination could aid in diagnosing retroperitoneal masses.