<prompt> All are true except regarding patch testDiagnose ABCDRead after 48 hoursAngry back IA false negative testT.R.U.E test  <response>: C. i.e. Angry back lit false negative test The gold standard method for the diagnosis of allergic dermatitis resulting from type IV delayed hypersenstivityQ. Such as allergic contact dermatitis ACD air borne contact dermatitis ABCDQ remains the patch test. It is read after 48 hours 2 daysQ Type 1 hypersensitivity eg atopic dermatitis is detected by prick test of debatable significance. And type IV delayed hypersensitivity eg contact dermatitis is diagnosd by patch skin test gold standard. So skin test can be done for Type I atophy type IV contact dermatitis. Type of hypersensitive reaction Clinical Syndrome Type I : IgE type AnaphylaxisQ AtopyQ prick test Type II : Cytolytic Antibody mediated damage? Cytotoxic Thrombocytopenia- agranulocytosis, hemolytic anemia etc. Type III : Immune Ahrus reaction complex Serum sickness Type IV : Delayed Tuberculosis Hypersensitivity Contact dermatitis patch testQ 