Unusual motion detected on real-time sonography inside a glomus tumor in the thigh

Glomus tumors are rare and many have been reported to have a hypervascular appearance on color or power Doppler sonography. We report a pathologically proven case of superficial glomus tumor within the thigh with no detectable color flow signals on color or power Doppler sonography. In addition, real-time sonography showed spontaneous motions within the tumor, which were not synchronized with vascular or respiratory motions, and misled the presurgical diagnosis of a suspected parasite in a patient who had direct contact with multiple animal species. The etiology of this internal motion remains hypothetical but, if reconfirmed, this finding may be a useful adjunctive sign for the diagnosis of glomus tumors.