<prompt> The below rash was seen in a person. He has a family history of asthma. What could be the most probable diagnosis?Seborrheic dermatitisAtopic dermatitisAllergic contact dermatitisErysipelas  <response>: Ref. Rooks Textbook of Dermatology, Pg 99 Allergic contact dermatitis is a form of dermatitiseczema caused by an allergic reaction to a material, called an allergen, in contact with the skin.PathogenesisAllergic contact dermatitis is a type 4 or delayed hypersensitivity reaction and occurs 4872 hours after exposure to the allergen. The mechanism involves CD4 T-lymphocytes, which recognise an antigen on the skin surface, releasing cytokines that activate the immune system and cause the dermatitis. 