Thanks for the query.
There is some possibility for lymphatic system
That can lead to disparity in the sizes of the limbs
So you once consult general surgeon
and get examined regarding this.
Check for lymph-nodal enlargement in any other sites of the body.
examinations are need.
Self examination of the breast helps in detecting any abnormality at the earliest.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429