Genetically informed studies of the personality characteristics typical of individuals with psychopathy have found moderate genetic (as well as non-genetic) influences. On the PPI, fearless dominance and impulsive antisociality were similarly influenced by genetic factors and uncorrelated with each other. Genetic factors may generally influence the development of psychopathy while environmental factors affect the specific expression of the traits that predominate. A study on a large group of children found more than 60% heritability for "callous-unemotional traits" and that conduct problems among children with these traits had a higher heritability than among children without these traits.

A study by Farrington of a sample of London males followed between age 8 and 48 included studying which factors scored 10 or more on the PCL:SV at age 48. The strongest factors included having a convicted parent, being physically neglected, low involvement of the father with the boy, low family income, and coming from a disrupted family. Other significant factors included poor supervision, harsh discipline, large family size, delinquent sibling, young mother, depressed mother, low social class, and poor housing. There has also been association between psychopathy and detrimental treatment by peers. However, it is difficult to determine the extent of an environmental influence on the development of psychopathy because of evidence of its strong heritability.

There is evidence that narcissistic personality disorder is heritable, and individuals are much more likely to develop NPD if they have a family history of the disorder. Studies on the occurrence of personality disorders in twins determined that there is a moderate to high heritability for narcissistic personality disorder.

However the specific genes and gene interactions that contribute to its cause, and how they may influence the developmental and physiological processes underlying this condition, have yet to be determined.

The causes of narcissistic personality disorder are unknown. Experts tend to apply a biopsychosocial model of causation, meaning that a combination of environmental, social, genetic and neurobiological factors are likely to play a role in formulating a narcissistic personality.

Malignant narcissism is a psychological syndrome comprising an extreme mix of narcissism, antisocial behavior, aggression, and sadism. Often grandiose, and always ready to raise hostility levels, the malignant narcissist undermines organizations in which they are involved, and dehumanizes the people with whom they associate.

Malignant narcissism is a hypothetical, experimental diagnostic category. Narcissistic personality disorder is found in the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-IV-TR), while malignant narcissism is not. As a hypothetical syndrome, malignant narcissism could include aspects of narcissistic personality disorder as well as paranoia. The importance of malignant narcissism and of projection as a defense mechanism has been confirmed in paranoia, as well as "the patient's vulnerability to malignant narcissistic regression".

Sadistic personality disorder is a personality disorder involving which appeared in an appendix of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-III-R). The later versions of the DSM (DSM-IV, DSM-IV-TR and DSM-5) do not include it.

The words "sadism" and "sadist" are derived from Marquis de Sade.

Sadistic personality disorder has been found to occur frequently in unison with other personality disorders. Studies have also found that sadistic personality disorder is the personality disorder with the highest level of comorbidity to other types of psychopathological disorders. In contrast, sadism has also been found in patients who do not display any or other forms of psychopathic disorders. One personality disorder that is often found to occur alongside sadistic personality disorder is conduct disorder, not an adult disorder but one of childhood and adolescence. Studies have found other types of illnesses, such as alcoholism, to have a high rate of comorbidity with sadistic personality disorder.

Researchers have had some level of difficulty distinguishing sadistic personality disorder from other forms of personality disorders due to its high level of comorbidity with other disorders.

Grandiosity refers to an unrealistic sense of superiority—a sustained view of oneself as better than others that causes the narcissist to view others with disdain or as inferior—as well as to a sense of uniqueness: the belief that few others have anything in common with oneself and that one can only be understood by a few or very special people. It also occurs in reactive attachment disorder.

Grandiosity is chiefly associated with narcissistic personality disorder, but also commonly features in manic or hypomanic episodes of bipolar disorder.

While narcissists are common, malignant narcissists are less common. A notable difference between the two is the feature of sadism, or the gratuitous enjoyment of the pain of others. A narcissist will deliberately damage other people in pursuit of their own selfish desires, but may regret and will in some circumstances show remorse for doing so, while a malignant narcissist will harm others and enjoy doing so, showing little empathy or regret for the damage they have caused.

Neurosis is a class of functional mental disorders involving chronic distress but neither delusions nor hallucinations. The term is no longer used by the professional psychiatric community in the United States, having been eliminated from the "Diagnostic and Statistical Manual of Mental Disorders" in 1980 with the publication of DSM III. It is still used in the .

Neurosis should not be mistaken for psychosis, which refers to a loss of touch with reality. Neither should it be mistaken for neuroticism, a fundamental personality trait proposed in the big Five personality traits theory.

There are many different neuroses: obsessive–compulsive disorder, obsessive–compulsive personality disorder, impulse control disorder, anxiety disorder, hysteria, and a great variety of phobias.

According to C. George Boeree, professor emeritus at Shippensburg University, the symptoms of neurosis may involve:

Neurosis may be defined simply as a "poor ability to adapt to one's environment, an inability to change one's life patterns, and the inability to develop a richer, more complex, more satisfying personality."

Multiple complex developmental disorder is likely to be caused by a number of different various genetic factors. Each individual with MCDD is unique from one another and displays different symptoms. Various neuropsychological disorders can also be found in family members of people with MCDD.

The Dorian Gray syndrome (DGS) denotes a cultural and societal phenomenon characterized by a man's extreme pride in his personal appearance and the fitness of his physique, which is accompanied by difficulties in coping with the requirements of psychological maturation and with the aging of his body.

The DGS is characterized by a triad of symptoms that overlap, and so combine diagnostic signs of dysmorphophobia, narcissistic character traits, and the immaturity of arrested development, which often are found in paraphilias.

To preserve ephemeral youth, the man afflicted with DGS tends to consume cosmetic products and services, hair-restoration procedures, anti-impotence drugs, and cosmetic surgery; hence, he might resist the psychosomatic and psychodynamic explanations of the syndrome. The term "Dorian Gray syndrome" refers to the protagonist of the novel "The Picture of Dorian Gray" (1891), an exceptionally handsome man whose hedonism and excessive self-love proved detrimental to the personal, social, and emotional aspects of his life, and who sought to escape the ravages of time and his own decadent lifestyle by having a supernatural portrait of himself age in his place.

The Dorian Gray syndrome arises from the concurring and overlapping clinical concepts of the narcissistic personality, dysmorphophobia, and paraphilia. Psychodynamically, the man afflicted with DGS presents an interplay among his narcissistic tendencies ("timeless beauty"), his arrested development (inability to psychologically mature), and his use of "medical lifestyle" products and services — hair restoration, drugs (for impotence, weight-loss, and mood modification), laser dermatology, and plastic surgery — in order to remain young.

Although the DGS patient displays diagnostic features of said mental disorders, the syndrome describes a common, underlying psychodynamics of mental illness, which is characterized by narcissistic defences against time-dependent maturation, expressed by actively seeking the timeless beauty of youth. The article "Das Dorian Gray syndrom" (2005) reported that approximately 3.0 per cent of the population of Germany present features of the Dorian Gray syndrome.

Pathological grandiosity has been associated with one of the two subtypes of Narcissistic Personality Disorder. (Gabbard, 1989) Characteristics of the narcissist-grandiose subtype (as opposed to the narcissist-vulnerable subtype) include:

- Being labeled the “oblivious narcissists”

- Observed lack of insight into the impact they have on others

- More likely to regulate self-esteem through overt self-enhancement

- Denial of weaknesses

- Inflated demands of entitlement

- Consistent anger in unmet expectations

- Devaluation of people that threaten self-esteem

- Diminished awareness of the dissonance between their expectations and reality, along with the impact this has on relationships

- Overt presentation of grandiose fantasies

- Conflict within the environment is generally experienced as external to these individuals and not a measure of their own unrealistic expectations

The differences between grandiose and vulnerable narcissist subtypes have been studied (Dickinson & Pincus, 2003):

The grandiosity section of the Diagnostic Interview for Narcissism (DIN) (Second edition) is as follows:

1. The person exaggerates talents, capacity and achievements in an unrealistic way.

2. The person believes in his/her invulnerability or does not recognize his/her limitations.

3. The person has grandiose fantasies.

4. The person believes that he/she does not need other people.

5. The person overexamines and downgrades other people, projects, statements, or dreams in an unrealistic manner.

Counterdependency is the state of refusal of attachment, the denial of personal need and dependency, and may extend to the omnipotence and refusal of dialogue found in destructive narcissism, for example.

Multiple complex developmental disorder (MCDD) is a research category, proposed to involve several neurological and psychological symptoms where at least some symptoms are first noticed during early childhood and persist throughout life. It was originally suggested to be a subtype of autistic spectrum disorders (PDD) with co-morbid schizophrenia or another psychotic disorder; however, there is some controversy that not everyone with MCDD meets criteria for both PDD and psychosis. The term "multiplex developmental disorder" was coined by Donald J. Cohen in 1986.

The roots of counterdependency can be found in the age-appropriate negativism of two-year-olds and teens, where it serves the temporary purpose of distancing one from the parental figure[s]. As Selma Fraiberg put it, the two-year-old "says 'no' with splendid authority to almost any question addressed to him...as if he establishes his independence, his separateness from his mother, by being opposite". Where the mother has difficulty accepting the child's need for active distancing, the child may remain stuck in the counterdependent phase of development because of developmental trauma.

In similar fashion, the teenager needs to be able to establish the fact of their separate mind to their parents, even if only through a sustained state of cold rejection; and again unresolved adolescent issues can lead to a mechanical counterdependence and unruly assertiveness in later life.

Katoptronophilia is a paraphilia for mirrors (the Greek word for "mirror" is "katoptron"). It may include activities such as having sex in front of mirrors, masturbating in front of mirrors, enacting other paraphilias in front of a mirror, having an orgy in front of a mirror, or enacting stripping fetishism in front of mirrors.

Enacting katoptronophiliac fantasies may involve constructing environments for erotic activity in which one is completely surrounded by mirrors, sometimes including even on the ceiling. A person who is a "katoptronophiliac" may put mirrors all over their house so they can have sex in any room in the house.

Many pornographic films show porn stars having sex in front of mirrors.

Many people enjoy having sex in front of mirrors and have mirrors in their bedrooms in which they can watch themselves have sex. They sometimes engage in this activity for their personal enjoyment. On a deeper level this could relate to the person's need to reflect and critique themselves, and also being on a mental state of narcissism. The person often is solely absorbed in themselves and likes to watch their actions so as to admire.

10-year survival rates for mucinous tumors is excellent in the absence of invasion.

In the case of borderline tumors confined to the ovary and malignant tumors without invasion, the survival rates are 90% or greater. In invasive mucinous cystadenocarcinomas, the survival is approximately 30%

Giant-cell lung cancers have long been considered to be exceptionally aggressive malignancies that grow very rapidly and have a very poor prognosis.

Many small series have suggested that the prognosis of lung tumors with giant cells is worse than that of most other forms of non-small-cell lung cancer (NSCLC), including squamous cell carcinoma, and spindle cell carcinoma.

The overall five-year survival rate in GCCL varies between studies but is generally considered to be very low. The (US) Armed Forces Institute of Pathology has reported a figure of 10%, and in a study examining over 150,000 lung cancer cases, a figure of 11.8% was given. However, in the latter report the 11.8% figure was based on data that included spindle cell carcinoma, a variant which is generally considered to have a less dismal prognosis than GCCL. Therefore, the likely survival of "pure" GCCL is probably lower than the stated figure.

In the large 1995 database review by Travis and colleagues, giant-cell carcinoma has the third-worst prognosis among 18 histological forms of lung cancer. (Only small-cell carcinoma and large-cell carcinoma had shorter average survival.)

Most GCCL have already grown and invaded locally and/or regionally, and/or have already metastasized distantly, and are inoperable, at the time of diagnosis.

Patient response to treatment will vary based on age, health, and the tolerance to medications and therapies.

Metastasis occurs in about 39% of patients, most commonly to the lung. Features associated with poor prognosis include a large primary tumor (over 5 cm across), high grade disease, co-existent neurofibromatosis, and the presence of metastases.

It is a rare tumor type, with a relatively poor prognosis in children.

In addition, MPNSTs are extremely threatening in NF1. In a 10-year institutional review for the treatment of chemotherapy for MPNST in NF1, which followed the cases of 1 per 2,500 in 3,300 live births, chemotherapy did not seem to reduce mortality, and its effectiveness should be questioned. Although with recent approaches with the molecular biology of MPNSTs, new therapies and prognostic factors are being examined.

Malignant germ cell tumors of the mediastinum are uncommon, representing only 3 to 10% of tumors originating in the mediastinum. They are much less common than germ cell tumors arising in the testes, and account for only 1 to 5% of all germ cell neoplasms.

Syndromes associated with mediastinal germ cell tumors include Hematologic Neoplasia and Klinefelter's syndrome.

Diet and lifestyle are believed to play a large role in whether colorectal polyps form. Studies show there to be a protective link between consumption of cooked green vegetables, brown rice, legumes, and dried fruit and decreased incidence of colorectal polyps.

Uterine sarcoma are rare, out of all malignancies of the uterine body only about 4% will be uterine sarcomas. Generally, the cause of the lesion is not known, however patients with a history of pelvic radiation are at higher risk. Most tumors occur after menopause.

Women who take long-term tamoxifen are at higher risk.