Can a PhD thesis be completed without a literature review section?

I have reviewed one thesis which my supervisor had supervised until 2013 and it was submitted with no literature review chapter or section; and the candidate passed!

Is this usual to see?

fairly unusual, but I assume they had covered some background in their data chapters? Some unis have no real structures to their theses.

The literature could have been reviewed as part of a chapter rather than as a distinct section. Not uncommon in the humanities certainly.