Narcissistic personality disorder is a condition in which there is an inflated sense of self-importance and an extreme preoccupation with one's self.
The cause of this disorder is unknown. Narcissistic personality disorder usually begins by early adulthood.
Moore DP, Jefferson JW. Narcissistic personality disorder. In: Moore DP, Jefferson JW, eds. Handbook of Medical Psychiatry. 2nd ed. Philadelphia, Pa: Mosby Elsevier; 2004: chap 140.
Young JQ. Narcissistic personality disorder. In: Ferri FF, ed. Ferri's Clinical Advisor 2008: Instant Diagnosis and Treatment. 1st ed. Philadelphia, Pa: Mosby Elsevier; 2008.