Culture of the lesion-with the classic presentation of herpes zoster, the clinical examination is diagnostic. a viral culture of the lesion provides the definitive diagnosis. herpes zoster (shingles) is caused by a reactivation of the varicella-zoster virus, the virus that causes chickenpox. a patch test is a skin test that involves the administration of an allergen to the surface of the skin to identify specific allergies. a biopsy would provide a cytological examination of tissue. in a woods light examination, the skin is viewed under ultraviolet light to identify superficial infections of the skin.