The bulk of the literature dedicated to narcissistic personality disorders over the last decade has largely focussed on the need to establish new and improved diagnosis models:
The attention to the narcissistic individual's external, symptomatic, or social interpersonal patterns — at the expense of his or her internal complexity and individual suffering — has also added to the diagnosis' low clinical Diagnosis utility and limited guidance for treatment. Recent studies and reviews have pointed to the need for change in the diagnostic approach to and formulation of narcissism.
Let's take a look at the standard diagnosis criteria of NPD, as set forth by the DSM-IV-TR, which 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.
According to this diagnostic manual, NPD is present when at least five of the following criteria are met:
has a grandiose sense of self-importance (e.g., exaggerates achievements and talents, expects to be recognized as superior without commensurate achievements)
is preoccupied with fantasies of unlimited success, power, brilliance, beauty, or ideal love
believes that he or she is "special" and unique and can only be understood by, or should associate with, other special or high-status people (or institutions)
requires excessive admiration
has a sense of entitlement, i.e., unreasonable expectations of especially favorable treatment or automatic compliance with his or her expectations
is interpersonally exploitative, i.e., takes advantage of others to achieve his or her own ends
lacks empathy: is unwilling to recognize or identify with the feelings and needs of others
is often envious of others or believes that others are envious of him or her
shows arrogant, haughty behaviors or attitudes

Now, with just a quick glance at this list, I am sure each one of my readers can think of at least a handful of people they know, who seem to meet many of these criteria. Not all of them must, of course, necessarily be suffering from pathological NPD, though some of them might be, and they might remain undiagnosed, due to the fact that the line between pathological and healthy narcissism is an extremely blurry one.
Ronnie Solan dedicated much of her work to attempting to establish these boundaries:
The process of narcissistic self-love is activated by three absolute narcissistic needs: (a) to experience an affective state of well-being (homeostasis) in the familiar and constant state of self-love; (b) to separate the familiar self from the unfamiliar non-self; and (c) to integrate or befriend the unfa- miliar yet "similar enough" non-self within the self in order to contain over-excitation.
Within a healthy narcissistic structure, these absolute needs must reach a state of equilibrium, which means that deciphering the familiar and befriending the unfamiliar (non-self) must be coherent and integral with the genuine identities of familiar self-codes. However, if one of these needs is incoherently regulated in relation to the others, the threat of narcissistic imbalance emerges, further imperiling the integrity of the self-codes.
What Solan calls the Diagnosis "narcissistic imbalance" can appear very elusive to the naked eye of the non-professional observer. The pathological narcissist, with his/her lack of empathy and sense of self-importance will be the last to acknowledge that he/she has a problem. Therefore, the call for help that might bring in a therapist capable of identifying and treating NPD may never come, especially if the individual in question is a high performer, which society tends to view as a sign of personal success.