Coarse liver cannot be put down to a single cause, but some of the causes may include drinking heavily currently or in the past, as this can seriously damage the liver, and a poor diet, leading in some cases to serious illnesses such as malnutrition. Again though, due to the wideness of this term, it is highly recommended that you visit a doctor to get the term in a use which is right for you.
If you have been diagnosed as having this in the hospital, ask them to tell you what is wrong in layman’s terms, as doctor’s language often goes over patients heads a little.
If you are asking this question in terms of food however, coarse liver is a term used to describe the cut of the liver, particularly in the meat spread Pate. Coarse liver pate means that the liver in the pate is in larger chunks, as opposed to Brussels or Ardennes, which are smoother varieties.