A 45 year old farmer has itchy erythematous papular lesions on face, neck, 'V' area of chest, dorsum 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 diagnose the condition would be –
This patient has :-

Itchy papular lesions on face, neck, V shaped area of chest, dorsum of hand.
Exacerbation in summer and improvement in winter.

Both of these are clinical clues for the diagnosis of photodermatoses.
"Photopatch test is used to confirm the diagnosis of photoallergic dermatosis".
Skin biopsy
Estimation of IgE levels in blood
Patch test
Intradermal prick test