Ultrasonographic and MR findings of alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare soft-tissue sarcoma, commonly occurring in children and adolescents. The tumor mostly involves the lower extremities. The prognosis of the patient depends on whether there is metastasis. We present a 19-year-old female with ASPS in her right lower leg. Grayscale and color Doppler ultrasound showed a well-defined hypoechoic lesion with hypervascularity and very low resistive index (RI). Magnetic resonance imaging revealed iso signal intensity to muscle on T1-weighted images, high signal intensity to muscle on T2-weighted images with signal voids, and good enhancement after gadolinium administration. In a mass with hypervascularity and very low RI on sonography and hypervascularity with flow voids on magnetic resonance imaging, ASPS should be considered.