A 55-year-old man presented to his general practitioner with sudden local discomfort in the left calf. His symptoms were atypical and vague. Subsequently, he was referred for diagnostic imaging. Ultrasound identified a well circumscribed nodular mass in the popliteal fossa with a diameter of approximately 25 mm and a heterogeneous, hypoechoic appearance (Fig. A). The origin of the mass was not entirely clear on US and subsequently a MRI study was performed.