Mayo Clinic: Narcissistic personality disorder
If you have narcissistic personality disorder, you may come across as conceited, boastful or pretentious. You often monopolize conversations. You may belittle or look down on people you perceive as inferior. You may feel a sense of entitlement — and when you don’t receive special treatment, you may become impatient or angry. You may insist on having “the best” of everything — for instance, the best car, athletic club or medical care.
At the same time, you have trouble handling anything that may be perceived as criticism. You may have secret feelings of insecurity, shame, vulnerability and humiliation. To feel better, you may react with rage or contempt and try to belittle the other person to make yourself appear superior. Or you may feel depressed and moody because you fall short of perfection.