Which of the following diagnoses should be included in the differential for a patient with a pruritic, papular rash?

In the case of a pruritic, papular rash, papular urticaria is a relevant diagnosis to consider because it typically presents in children as raised, itchy bumps that may appear in clusters. This condition is often related to insect bites, such as from fleas or mosquitoes, which can provoke an allergic reaction leading to the characteristic papular lesions. Papular urticaria is particularly common in young children, and its clinical features align closely with the described rash.

The other options, while they may present with various types of rashes, have different characteristics that distinguish them from papular urticaria. For instance, scabies typically presents with intense itching, especially at night, and shows burrows or vesicles between fingers and other common sites, rather than a generalized papular rash. Erythema nodosum appears as painful, red nodules, often located on the shins, and is usually associated with systemic conditions or infections rather than being purely pruritic. Psoriasis generally features well-defined, silvery scales over red plaques, and while it can itch, it does not typically present as a papular rash.

Thus, including papular urticaria in the differential for a pruritic, papular rash is