What Causes Indentation At The Anal Region?

Hi there My boyfriend is overseas at the moment and has discovered quite an indent in the area between the balsa and anus but very close to his anus. It s not painful or itchy but is has formed by itself and he is concerned as to what it could be. I have a photo of it if That would help you determine what it could be. His in a forien speaking country so is hesitant to see a dr.