Is there an equivilent of c#\'s #region in PHP?
No, there's nothing directly in the language.
But every decent editors allow some kind of markup to allow this.
For example in Netbeans :
//
...any code...
//
This syntax also works in all the Intellij IDEA editor family, see http://blog.jetbrains.com/webide/2012/03/new-in-4-0-custom-code-folding-regions/
You can also emulate the feature in Eclipse via a plugin : Code folding plugin for Eclipse?
Visual Studio Code includes it since version 1.19 :
#region user description
...any code...
#endregion