what is mild systemic disease
A systemic disease is one that affects the body as a whole (the whole system) or one that affects most or all of the organs in a particular system (digestive system, respiratory system, etc). Mild systemic disease is a term to indicate some disease that is affecting a body system but is well controlled or not causing any functional limitations. http://my.clevelandclinic.org/services/anesthesia/hic_asa_physical_classification_system.aspx
There is no such thing as a mild systemic disease because when a disease is considered to be systemic it means it affects a majority of organs in our body. One example of a systemic disease is SLE or systemic lupus erythematosus.