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Wood’s Lamp Examination

Wood’s Lamp Examination. Wood’s Lamp Mercury vapour UV lamp with an incoorporated Wood’s filter (barium silicate glass with 9% metal oxide. Emits UV rays in the wavelength of 360 nm. Wood’s Lamp Examination. Uses Diagnosis of taenia capitis Gives rise to greenish fluorescence

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Wood’s Lamp Examination

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  1. Wood’s Lamp Examination Wood’s Lamp • Mercury vapour UV lamp with an incoorporated Wood’s filter (barium silicate glass with 9% metal oxide. • Emits UV rays in the wavelength of 360 nm

  2. Wood’s Lamp Examination Uses • Diagnosis of taeniacapitis • Gives rise to greenish fluorescence • Microsporum species and trychophytonschoenleonii are the main fluorescing species • Diagnosis of bacterial infections • Erythrasema gives a coral pink colouration

  3. Examination of extent of pigmentary disorders • Easily accentuates the distinction between slightly hypopigmented and normal skin areas • Enhances the hypopigmented lesions e.g. ash leaf macules in light skin patients • Diagnosis of porphyria • Pinkish red or orangish red fluoresence in urine which is intensified on addition of dilute HCl • Similar fluoresence in faeces

  4. Detection of drug deposits • Demonstrates yellow fluoroscence deposits in teeth and mepacrine in nails

  5. Mycologic Examination KOH Mount • Sample is put on a glass slide and an aquous solution of 20% KOH is addedbefore applying the cover slip • Examine the slide under microscope after 20-30 min • Fungal hyphae are easily visible

  6. KOH Mount Specimens to be taken

  7. Diagnosis of Scabies • Presence of mite,ova or faeces in scrapings of paules,vesiculesor burrows confirms the diagnosis METHOD • Drop of mineral oil placed on a sterile scalpel blade is applied onto a lesion which is then scrapped vigrously till tiny flecks of blood are visible in the oil.The material is transferred onto a glass slide and examined for mites,ova or faeces

  8. Tzanck Test • Cytological examination of skin blisters • Test is done in vescicular and bullous lesions METHOD • Early lesion is choosen,deroofed and the excess fluid is gently blotted with gauze.The floor of the blister is then scrapped gently with a scalpel blade and the material so obtained is spread on a glass slide and stained with Giemsa stain

  9. Tzanck Test Role of Tzack smear in diagnosis of skin conditions

  10. PATCH TESTS • Detects antigens responsible for type IV allergy (allergic contact dermatitis) Antigens Used • Test the suspected antigen as well as antigens which are present in the material which is likely to be used as a substitute • If theseare not known a standard battery of antigens can be used

  11. Interpretations of patch tests

  12. PHOTOPATCH TESTING • Done to establish cause in photoallergic contact dermatitis METHOD • Antigens are applied,as in routine pach testing but in duplicate. • At 24 hrs , one set of patches are irradiated with UVA

  13. Interpretation of photopatch test

  14. SKIN BIOPSY Techniques of Taking Biopsy Two common techniques • Punch biopsy • Scalpel biopsy

  15. Punch Biopsy • Punch biopsies can be done rapidly, with or without suturing of the wound • A punch-biopsy instrument of appropriate size is needed METHOD • A local anesthetic is usually injected at the site. The operator rotates the instrument until it penetrates to the subcutaneous level. The circle of tissue is then removed. Bleeding can be stopped with pressure or by the use of one or two sutures. An elliptical wound instead of a circular wound can be produced by stretching the skin perpendicular to the desired suture line before the punch is rotated. The resultant scar, after suturing, is neater • Punch biopsies are inadequate for evaluation of vesiculobullous diseases

  16. Scalpel Biopsy • A scalpel is used to slice off a lesion • Performed superficially or deeply • Hemostasis can be accomplished by pressure, light electrosurgery, Monsel solution, or aluminum chloride solution • Not recommended for excision of melanocytic lesions

  17. Processing of Skin Biopsy • Apart from routine H&E staining special stains can be used for various tissues and to identify different organisims

  18. Precautions While Taking a Skin Biopsy • Biopsy a new lesion or active edge of a proressing lesion • Avoid legs (slow healing), upper trunk(because of tendency of keloid formation),exposed parts(cosmetic objections) & bony prominces • Do not crush the tissue • Place the proper fixative • Label samples correctly

  19. THANK YOU

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