Wood lamp is used to diagnose?

Ans. b (Tinea versicolor). (Ref. Harrison, Internal Medicine, 15th ed., 308)DIAGNOSTIC TECHNIQUES IN SKIN DISEASES# Skin biopsy# KOH preparation: To identify hyphae in dermatophytosis, e.g. fragmented hyphae with spores pseudohyphae, yeast in Candida.# Tzanck smear. Staining with Giemsa/Wright stain. To identify herpes infection (multinucleated giant cells)# Diascopy: To assess if lesion blanches with pressure, e.g. haemangioma, granuloma ("apple jelly" app.)# Wood's lightAamp: 360 nm UV light used. Specific finding as following may be diagnostic:- Erythrasma =- Wound with pseudomonas =- Tinea capitis (microspora canis/audouini) =- Freckles =- Hyperpigmentation =- Vitiligo =- Ash leaf spots=- Demonstration of tinea versicolorcoral red colorpale blueyellow fluorescenceaccentuatedfadestotally whitetuberous sclerosis# Patch testTINEA VERSICOLOR:# Causative agent: Malassezia furfur.# Macules of variegated color, growing rapidly.# KOH preparation reveals classic "Spaghetti & meat balls" appearance.# Topical Rx with selenium sulphide lotion and ketoconazole shampoo.PITYRIASIS ROSEA:# Causative agent: HHV 7.# Herald patch and Collarette scale lesions# "Christmas-tree"pattern of annular patches on trunk.# Rx: Antihistaminics, steroids and at times UVA therapy may be needed.DiseaseClinical featuresEtiologic agentImpetigoHoney-colored crusted papules, plaques, or bullaeGroup A streptococcus and Staphylococcus aureusDermatophytosisInflammatory or noninflammatory annular scaly plaques; may have hair loss; groin involvement, spares scrotum; hyphae on KOH preparationTrichophyton, Epidermophyton, or Microsporum sp.CandidiasisInflammatory papules and plaques with satellite pustules, frequently in intertriginous areas; may involve scrotum; pseudohyphae on KOH preparationCandida albicans & other Candida speciesTinea versicolorHyper- or hypopigmented scaly patches on the trunk; characteristic mixture of hyphae and spores ("spaghetti and meatballs") on KOH preparationMalassezia furfur