Sonographic and clinical features of angioleiomyoma presenting as a painful Achilles tendon mass

Angioleiomyomas are benign soft tissue tumors arising from the smooth muscle cells of blood vessels. These tumors are relatively infrequent and typically present as small (<2 cm), freely movable, painful masses. Although most frequently reported in the lower extremity and in middle-aged female patients, angioleiomyomas can be found throughout the body in male and female adults of all ages. Sonography is often used in the initial evaluation of soft tissue masses; therefore, sonographers should be familiar with the clinical and imaging features of angioleiomyomas. We report a case of a slowly growing, lateral Achilles tendon mass initially evaluated by sonography and subsequently by magnetic resonance imaging (MRI). Surgical excision confirmed the diagnosis of angioleiomyoma, likely arising from a branch of the lesser saphenous vein. The clinical and imaging features of this infrequent tumor are reviewed.