A 45 year old farmer has itchyerythematous papular lesions on face, neck, 'V' area of chest, dorsmn of hands and forearms for 3 years.The lesions are more severe in summers and improve by 75% in winters. The most appropriate test to diagnos(.e.titil:) condition would be -: (A) Skin biopsy, (B) Estimation of IgE levels in blood, (C) photo Patch Test, (D) Intraderrnal prick test
Answer is C. The photo-patch test is conducted to examine the influence of rays when a chemical substance is placed on the skin. Twenty- four to 48 hours after a material that is suspected of causing pho- tosensitive disease is pasted on the skin, the site is exposed to UV rays. Ref Harrison20th edition pg 1234