Final answer:
An exanthematous (morbiliform) drug eruption describes a hypersensitive reaction to a drug that results in a measles-like rash and is categorized as a type of delayed hypersensitivity.
Step-by-step explanation:
The hypersensitive reaction to a drug characterized by a cutaneous eruption that mimics a measles-like viral rash is known as an exanthematous (morbiliform) drug eruption.
This condition is a type of delayed hypersensitivity where after the first sensitization, subsequent exposure to the drug causes T cells to release cytokines, which can result in a widespread rash resembling measles.
It is not as localized as contact dermatitis, which involves redness and swelling on the skin in contact with an allergen like nickel or poison ivy.
Unlike immediate hypersensitivity reactions such as drug induced acute urticaria, which results in hives and is mediated by IgE antibodies, exanthematous drug eruptions develop over several days.
Treatment typically involves stopping the offending drug and may include antihistamines or corticosteroids to reduce inflammation and itching.