A medical condition is a broad term that includes all diseases, lesions, and disorders.
While the term medical condition generally includes mental illnesses, in some contexts the term is used specifically to denote any illness, injury, or disease except for mental illnesses. The Diagnostic and Statistical Manual of Mental Disorders (DSM) uses the term "general medical condition" to refer to all diseases, illnesses, and injuries except for mental disorders.
As it is more value-neutral than terms like disease, people sometimes prefer the term "medical condition."
The term medical condition is also a synonym for medical state, which describes an individual patient's current state from a medical standpoint.

Adapted from Wikipedia, the free encyclopedia. Internet. Accessed on June 14, 2016.