**Question:** Gold poisoning leading to exfoliative dermatitis is treated by –

**Core Concept:** Gold poisoning, also known as auricular necrosis, is a severe skin reaction that occurs in individuals with long-standing gold allergy. Exfoliative dermatitis is a type of skin inflammation characterized by the shedding of dead skin cells. Treatment options for gold poisoning aim to reduce the exposure to gold while addressing the skin symptoms.

**Why the Correct Answer is Right:**

Correct Answer: **C. Sodium thiosulfate**

Explanation: Sodium thiosulfate (STS) serves as a neutralizing agent for gold ions, reducing their toxicity and thereby counteracting the skin toxicity caused by gold poisoning. STS works by forming a complex with gold ions, preventing them from binding to proteins and causing skin damage. This treatment option is crucial in managing gold poisoning leading to exfoliative dermatitis.

**Why Each Wrong Option is Incorrect:**

A. **Calcineurin inhibitors (e.g., cyclosporine):** These immunosuppressive agents are not suitable for treating gold poisoning as they are primarily used for suppressing the immune system in conditions like organ transplantation or autoimmune disorders. They do not neutralize gold ions or address the skin toxicity directly.

B. **Antihistamines:** Antihistamines are primarily used to treat allergic reactions, but they do not address the underlying gold poisoning or neutralize gold ions, making them an incorrect choice for treating gold poisoning-induced exfoliative dermatitis.

C. **Sodium thiosulfate (STS):** As mentioned earlier, STS is the correct treatment option. It works by neutralizing gold ions, reducing their toxicity, and preventing skin damage.

D. **Topical corticosteroids:** Topical corticosteroids are used for treating skin inflammation and allergic reactions but do not address gold poisoning or neutralize gold ions. Therefore, they are an incorrect choice for treating gold poisoning-induced exfoliative dermatitis.

**Clinical Pearl:**

In cases of gold poisoning and exfoliative dermatitis, early initiation of sodium thiosulfate administration can help prevent further skin damage and improve the prognosis.

**Correct Answer Explanation:**

Sodium thiosulfate (STS) is the correct answer because it effectively counteracts the toxic effects of gold ions by forming gold-thiosulfate complexes. This neutralizes the toxic gold ions, reducing their interaction with skin proteins and preventing further damage.