PS: Just throwing this out here... Something I just stumbled upon in an article about, of all people, Donald Trump???
Definitions from the official DSM manual.
Bolding and underlining are mine.
"narcissism, as defined by DSM5, consists of “impairments in self function” — either identity (“excessive reference to others for self-definition and self-esteem regulation”) or self-direction (“goal-setting is based on gaining approval from others”), with “impairments in interpersonal functioning” — either empathy or intimacy (“relationships largely superficial and exist to serve self-esteem regulation..little genuine interest in others...)."