This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
A 55-year-old male, with uncontrolled diabetes mellitus and hypeension, developed severe air-borne contact dermatitis. The most appropriate drug for his treatment would be: 
Select and explain. 
A. Systemic coicosteroids, B. Thalidomide, C. Azathioprine, D. Cyclosporine
C: Azathioprine
Answer: C: Azathioprine 
Explanation: C i.e. Azathioprine In contact dermatitis, the allergic reaction is mediated by delayed hypersensitivity (cell mediated immunity). It is treated by: - Antihistamincis - Steroids (topical/systemic) - Agents depressing cell mediated immunity as cyclosporine, tacrolimus, azathioprine