In: Psychology
Somatic disorders are related to irrational feelings and thoughts about some physical ailment that in reality do not have any medical cause. Dissociative disorders are completely different as it is related to dissociation with oneself. People with dissociative disorders have problems recognizing themselves and identity formation.
The factitious disorder and malingering are more or less the same in terms of making up or faking some physical or psychiatric illness. They differ in terms of cause. Malingering is oriented to accomplish some goal but fictitious disorder highlights - not having any relevant cause or goal to achieve.
Psychoanalysts study these disorders in terms of early/initial childhood traumas/experiences and internal unconscious conflict. They are treated by long sessions of psychoanalytic therapy which involves identifying the conflicting thoughts or drives making the client overcome these conflicts.