A 63-year-old man with a history of type 2 diabetes mellitus underwent a screening duplex and ultrasound scan of the leg arteries. Although he had no symptoms, the short-axis views of the inguinal region showed a mouse-shaped image formed by the normal femoral artery at bifurcation and by an enlarged and incompressible femoral vein (fig 1). This hypoechoic appearance is typical of fresh venous thrombosis. The patient was discharged with a prescription of enoxaparin and warfarin.

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Figure 1 Short-axis view showing a mouse-shaped image caused by the normal femoral artery at bifurcation, coupled with an enlarged and incompressible femoral vein typical of fresh venous thrombosis.

Deep vein thrombosis (DVT) in the lower limbs is known to present asymptomatically in at-risk individuals, with the potential of it not being recognised with possibly fatal consequences. A compression ultrasound scan of the femoral and popliteal veins is the most widely accepted screening test for DVT of the lower extremities.1 It is easy to perform, is reproducible, inexpensive and can be carried out at the patient’s bed.

Although the term “incidentaloma” was originally used to indicate a mass discovered by chance at the adrenal level, it is currently employed to indicate any asymptomatic lesion identified accidentally, especially during ultrasonography examination.

Since its creation in 1928 by Walt Disney, Mickey Mouse has been the most popular cartoon character worldwide. With a bit of humour, we report the “Mickey Mouse sign” shown in this case as an easy-to-remember appearance of venous thrombosis of the leg. This ultrasonographic figure is perhaps the furthest that photography can get from art.