Child 3 years-old with complaints of lesion in the popliteal area.
At US of popliteal area at side of complaints there is a classical Baker's cyst comma sign in the cross-scan of popliteal area - comma's tail - a channel of communication with the joint.
Interestingly, that in the contralateral popliteal area it is also visible a "comma's tail" without cysts - anisotropic effect (hypoechogenicity) taking place in the area of tendon - to the question of the informativeness of the comma sign.
