The type of personality disorder that best describes Thomas’ behavior is the narcissistic. The narcissistic personality disorder makes a person to have an obsession to one ’s self or having strong desire or interest to self which could be seen in the scenario in which Thomas has been paying attention and has been participating in the group meeting as he is the one talking, but when someone else had started to talk and it wasn't him anymore, he decided to excuse himself which exemplifies the behavior of being a narcissistic.