A 64-year-old man on the inpatient geriatric psychiatric unit believes he has a rash, even though no evidence has documented it in a medical workup. When he is told that no one can see this rash, he says the reason is because it is “on the inside.” What type of delusion is this?

Choice A reason: Bizarre delusions are implausible and not understandable within the context of cultural norms, such as believing aliens implanted a device in one's brain. The belief in an internal rash is not bizarre—it is medically conceivable, though unfounded. Choice B reason: Referential delusions involve the belief that external events, objects, or people have special meaning or are directed at the individual. This does not apply to the patient's belief about having a rash. Choice C reason: Nihilistic delusions involve beliefs that one is dead, does not exist, or that the world is ending. These are often seen in severe depression or psychotic states but are unrelated to somatic complaints. Choice D reason: Somatic delusions involve false beliefs about bodily functions or sensations. The patient’s belief that he has a rash “on the inside” despite no physical evidence is a classic example of a somatic delusion.