Get name of class that implements an interface

I have some entities, that may or may not inherit from other objects, but they will implement an interface, lets call it IMyInterface.

public interface IMyInterface {
    long MyPropertyName { get; set; }
}

An object will always implement this interface, but it may have been implemented on a class that the object inherits from. How can i get the name of the class that has this interface implemented?

Examples should give these results

public class MyClass : IMyInterface {

}

public class MyHighClass : MyClass {

}

public class MyPlainClass {

}

public class PlainInheritedClass : MyPlainClass, IMyInterface {

}

If i pass in MyClass, it should return MyClass, because MyClass implements the interface.

If i pass in MyHighClass, it should return MyClass, because MyClass was inherited, and it implements the interface.

If i pass in PlainInheritedClass, it should return PlainInheriedClass, because it inherited from MyPlainClass, but that did not implement the interface, PlainInheritedClass did