Pathological narcissism is a pattern of traits and behaviours which signify infatuation and obsession with one's self to the exclusion of all others and the egotistic and ruthless pursuit of one's gratification, dominance and ambition.
Most narcissists (50-75%, according to the DSM-IV-TR) are men.
The Narcissistic Personality Disorder (NPD) is one of a "family" of personality disorders (known as "Cluster B").
Other members of Cluster B are Borderline PD, Antisocial PD and Histrionic PD.
NPD is often diagnosed with other mental health disorders ("co-morbidity") ? or with substance abuse and impulsive and reckless behaviours ("dual diagnosis").
NPD is new (1980) mental health category in the Diagnostic and Statistics Manual (DSM).
There is only scant research regarding narcissism. But what there is has not demonstrated any ethnic, social, cultural, economic, genetic, or professional predilection to NPD.
It is estimated that 0.7-1% of the general population suffer from NPD.
The lifetime prevalence rate of NPD is approximately 0.5-1 percent; however, the estimated prevalence in clinical settings is approximately 2-16 percent. Almost 75 percent of individuals diagnosed with NPD are male (APA, DSM IV-TR 2000)."
From the Abstract of Psychotherapeutic Assessment and Treatment of Narcissistic Personality Disorder By Robert C. Schwartz,Ph.D., DAPA and Shannon D. Smith, Ph.D., DAPA (American Psychotherapy Association, Article #3004 Annals July/August 2002)
Pathological narcissism was first described in detail by Freud.
Other major contributors are: Klein, Horney, Kohut, Kernberg, Millon, Roningstam, Gunderson, Hare.
The onset of narcissism is in infancy, childhood and early adolescence. It is commonly attributed to childhood abuse and trauma inflicted by parents, authority figures, or even peers.
There is a whole range of narcissistic reactions ? from the mild, reactive and transient to the permanent personality disorder.
Narcissistic Supply is outside attention ? usually positive (adulation, affirmation, fame, celebrity) ? used by the narcissist to regulate his labile sense of self-worth.
Narcissists are either "cerebral" (derive their Narcissistic Supply from their intelligence or academic achievements) or "somatic" (derive their Narcissistic Supply from their physique, exercise, physical or sexual prowess and romantic or physical "conquests").
Narcissists are either "classic" [see definition below] or they are "compensatory", or "inverted" [see definitions here: "The Inverted Narcissist"].
The classic narcissist is self-confident, the compensatory narcissist covers up in his haughty behaviour for a deep-seated deficit in self-esteem, and the inverted type is a co-dependent who caters to the emotional needs of a classic narcissist.
NPD is treated in talk therapy (psychodynamic or cognitive-behavioural). The prognosis for an adult narcissist is poor, though his adaptation to life and to others can improve with treatment. Medication is applied to side-effects and behaviours (such as mood or affect disorders and obsession-compulsion) ? usually with some success.
The ICD-10, the International Classification of Mental and Behavioural Disorders, published by the World Health Organisation in Geneva  regards Narcissistic Personality Disorder (NPD) as "a personality disorder that fits none of the specific rubrics". It relegates it to the category "Other Specific Personality Disorders" together with the eccentric, "haltlose", immature, passive-aggressive, and psychoneurotic personality disorders and types.
The American Psychiatric Association, based in Washington D.C., USA, publishes the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, Text Revision (DSM-IV-TR)  where it provides the diagnostic criteria for the Narcissistic Personality Disorder.
The DSM defines NPD as "an all-pervasive pattern of grandiosity (in fantasy or behaviour), need for admiration or adulation and lack of empathy, usually beginning by early adulthood and present in various contexts."
The DSM specifies nine diagnostic criteria. For NPD to be diagnosed, five (or more) of these criteria must be met.
[In the text below, I have proposed modifications to the language of these criteria to incorporate current knowledge about this disorder. My modifications appear in bold italics.]
[My amendments do not constitute a part of the text of the DSM-IV-TR, nor is the American Psychiatric Association (APA) associated with them in any way.]
Proposed Amended Criteria for the Narcissistic Personality Disorder
Feels grandiose and self-important (e.g., exaggerates accomplishments, talents, skills, contacts, and personality traits to the point of lying, demands to be recognised as superior without commensurate achievements);
Is obsessed with fantasies of unlimited success, fame, fearsome power or omnipotence, unequalled brilliance (the cerebral narcissist), bodily beauty or sexual performance (the somatic narcissist), or ideal, everlasting, all-conquering love or passion;
Firmly convinced that he or she is unique and, being special, can only be understood by, should only be treated by, or associate with, other special or unique, or high-status people (or institutions);
Requires excessive admiration, adulation, attention and affirmation ? or, failing that, wishes to be feared and to be notorious (Narcissistic Supply);
Feels entitled. Demands automatic and full compliance with his or her unreasonable expectations for special and favourable priority treatment;
Is "interpersonally exploitative", i.e., uses others to achieve his or her own ends;
Devoid of empathy. Is unable or unwilling to identify with, acknowledge, or accept the feelings, needs, preferences, priorities, and choices of others;
Constantly envious of others and seeks to hurt or destroy the objects of his or her frustration. Suffers from persecutory (paranoid) delusions as he or she believes that they feel the same about him or her and are likely to act similarly;
Behaves arrogantly and haughtily. Feels superior, omnipotent, omniscient, invincible, immune, "above the law", and omnipresent (magical thinking). Rages when frustrated, contradicted, or confronted by people he or she considers inferior to him or her and unworthy.
(1) Alford, C. Fred - Narcissism: Socrates, the Frankfurt School and Psychoanalytic Theory - New Haven and London, Yale University Press - 1988
(2) Fairbairn, W. R. D. - An Object Relations Theory of the Personality - New York, Basic Books, 1954
(3) Freud S. - Three Essays on the Theory of Sexuality (1905) - Standard Edition of the Complete Psychological Works of Sigmund Freud - Vol. 7 - London, Hogarth Press, 1964
(4) Freud, S. - On Narcissism - Standard Edition - Vol. 14 - pp. 73-107
(5) Golomb, Elan - Trapped in the Mirror : Adult Children of Narcissists in Their Struggle for Self - Quill, 1995
(6) Greenberg, Jay R. and Mitchell, Stephen A. - Object Relations in Psychoanalytic Theory - Cambridge, Mass., Harvard University Press, 1983
(7) Grunberger, Bela - Narcissism: Psychoanalytic Essays - New York, International Universities Press - 1979
(8) Guntrip, Harry - Personality Structure and Human Interaction - New York, International Universities Press - 1961
(9) Horowitz M.J. - Sliding Meanings: A defense against threat in narcissistic personalities - International Journal of Psychoanalytic Psychotherapy - 1975;4:167
(10) Jacobson, Edith - The Self and the Object World - New York, International Universities Press - 1964
(11) Kernberg O. - Borderline Conditions and Pathological Narcissism - New York, Jason Aronson, 1975
(12) Klein, Melanie - The Writings of Melanie Klein - Ed. Roger Money-Kyrle - 4 vols. - New York, Free Press - 1964-75
(13) Kohut M. - The Analysis of the Self - New York, International Universities Press, 1971
(14) Lasch, Christopher - The Culture of Narcissism - New York, Warner Books, 1979
(15) Lowen, Alexander - Narcissism : Denial of the True Self - Touchstone Books, 1997
(16) Millon, Theodore (and Roger D. Davis, contributor) - Disorders of Personality: DSM IV and Beyond - 2nd ed. - New York, John Wiley and Sons, 1995
(17) Millon, Theodore - Personality Disorders in Modern Life - New York, John Wiley and Sons, 2000
(18) Roningstam, Elsa F. (ed.) - Disorders of Narcissism: Diagnostic, Clinical, and Empirical Implications - American Psychiatric Press, 1998
(19) Rothstein, Arnold - The Narcissistic Pursuit of Reflection - 2nd revised ed. - New York, International Universities Press, 1984
(20) Schwartz, Lester - Narcissistic Personality Disorders - A Clinical Discussion - Journal of Am. Psychoanalytic Association - 22 (1974): 292-305
(21) Stern, Daniel - The Interpersonal World of the Infant: A View from Psychoanalysis and Developmental Psychology - New York, Basic Books, 1985
(22) Vaknin, Sam - Malignant Self Love - Narcissism Revisited - Skopje and Prague, Narcissus Publications, 1999-2004
(23) Zweig, Paul - The Heresy of Self-Love: A Study of Subversive Individualism - New York, Basic Books, 1968