Narcissistic Personality Disorder (NPD) is a psychological disorder whereby the individual exhibits persistent pattern of grandiosity, imagination of unlimited power or importance, and the need for admiration or special treatment (Kacel, Ennis and Pereria, 2017). Most individuals with this disorder show how impulsive, volatile, and attention-seeking they are. Most times they suffer from low self-esteem, and unstable interpersonal relationships that result in a pervasive pattern of interpersonal problems, occupational problems, and significant psychosocial distress ( Stone, Segal, Krus, 2021).
The diagnostic criteria for this disorder according to DSM-5
A pervasive pattern of grandiosity (in fantasy or behavior), need for admiration, and lack of empathy, beginning by early adulthood and present in a variety of contexts, as indicated by five (or more) of the following (APA, 2013):

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, 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 (APA, 2013)

Psychotherapy and psychopharmacologic treatment
            Psychotherapy is strongly recommended in this case. Treatment could be individual psychotherapy—specifically, psychoanalytic psychotherapy, group, family, and or couples therapy, as well as cognitive-behavioral therapy (CBT) (Ronningstam, 2014).
            As far as the pharmacologic aspect of treatment is concerned, there are no specific medications for this disorder unless the individual has other underlying mental health conditions.
I have not had a client or experienced one with this disorder yet.
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders
(5th ed.). Washington, DC: Author.
Kacel, E. L., Ennis, N., & Pereira, D. B. (2017). Narcissistic Personality Disorder in Clinical
Health Psychology Practice: Case Studies of Comorbid Psychological Distress and Life-Limiting Illness. Behavioral Medicine, 43(3), 156–164. https://doi-org.ezp.waldenulibrary.org/10.1080/08964289.2017.1301875
Ronningstam, E. (2014). Introduction to the special series on “Narcissistic personality disorder—
new perspectives on diagnosis and treatment.” Personality Disorders, 5(4), 419–421. https://doi-org.ezp.waldenulibrary.org/10.1037/per0000093
Stone, L. E., Segal, D. L., & Krus, G. C. (2021). Relationships between pathological narcissism
and maladaptive personality traits among older adults. Aging & Mental Health, 25(5), 930–935. https://doi-org.ezp.waldenulibrary.org/10.1080/13607863.2020.1725802