## **Core Concept**
The condition described for the 9-year-old boy, with multiple itchy erythematous wheals all over the body, is indicative of **acute urticaria**. Urticaria, also known as hives, is a common skin condition characterized by the appearance of wheals (raised, itchy areas of skin). It can be caused by allergic reactions, infections, or other factors.

## **Why the Correct Answer is Right**
The best treatment for acute urticaria, especially in children, primarily involves **antihistamines**. These medications are effective in reducing the itching and the appearance of wheals. They work by blocking histamine, a substance in the body that causes the symptoms of allergy, including urticaria.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While corticosteroids can be used in severe cases of urticaria, they are not the first line of treatment for acute urticaria without severe symptoms, especially in children, due to their potential side effects.
- **Option B:** This option seems to be missing, but typically, treatments like antibiotics would not be appropriate for urticaria unless there's a clear indication of a bacterial infection causing the urticaria.
- **Option D:** This option is also missing but typically would not represent a standard first-line treatment for acute urticaria.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **second-generation antihistamines** (like loratadine or cetirizine) are preferred over first-generation antihistamines (like diphenhydramine) for the treatment of urticaria in children due to their efficacy and better side effect profile, particularly less sedation.

## **Correct Answer:** .