nombriliste

[alan gould]

this concept of being obsessed w ur navel or any part of ur body is totally foreign to english.  is this a common way of saying a person is self-centered?  

un nombril - navel, belly button

il est très nombriliste. - he is very self-centered

se prendre pour le nombril du monde (inf) - to think very highly of oneself

se regarder le nombril (inf) - to navel-gaze

[George Hunt]

Hardly totally foreign to English.

https://www.merriam-webster.com/dictionary/navel-gazing

Definition of navel-gazing
: useless or excessive self-contemplation

Other parts of the body can be centres for one's attention and are frequently  used to describe character traits.

[alan gould]

never heard of it in the US.  

[George Hunt]

Surprising  . 

I can't disagree of course but it does seem to include it here

https://en.oxforddictionaries.com/definition/us/navel-gazing

Perhaps it is less commonly used(it is not particularly common here either).

[Chantal Savignat]

se regarder le nombril : Not really common but not unusual.

"se prendre pour le nombril du monde" : we rather say "il se prend pour le centre du monde"

nombriliste : unusual. we rather use "egocentrique".