TAILIEUCHUNG - Chapter 052. Approach to the Patient with a Skin Disorder (Part 8)

Tzanck Smear A Tzanck smear is a cytologic technique most often used in the diagnosis of herpesvirus infections [herpes simplex virus (HSV) or varicella zoster virus (VZV)] (see Figs. 173-1 and 173-3). An early vesicle, not a pustule or crusted lesion, is unroofed, and the base of the lesion is scraped gently with a scalpel blade. The material is placed on a glass slide, air-dried, and stained with Giemsa or Wright's stain. Multinucleated epithelial giant cells suggest the presence of HSV or VZV; culture or immunofluorescence testing must be performed to identify the specific virus. Diascopy Diascopy is designed to assess. | Chapter 052. Approach to the Patient with a Skin Disorder Part 8 Tzanck Smear A Tzanck smear is a cytologic technique most often used in the diagnosis of herpesvirus infections herpes simplex virus HSV or varicella zoster virus VZV see Figs. 173-1 and 173-3 . An early vesicle not a pustule or crusted lesion is unroofed and the base of the lesion is scraped gently with a scalpel blade. The material is placed on a glass slide air-dried and stained with Giemsa or Wright s stain. Multinucleated epithelial giant cells suggest the presence of HSV or VZV culture or immunofluorescence testing must be performed to identify the specific virus. Diascopy Diascopy is designed to assess whether a skin lesion will blanch with pressure as for example in determining whether a red lesion is hemorrhagic or simply blood-filled. Urticaria Fig. 52-11 will blanch with pressure whereas a purpuric lesion caused by necrotizing vasculitis Fig. 52-4 will not. Diascopy is performed by pressing a microscope slide or magnifying lens against a lesion and noting the amount of blanching that occurs. Granulomas often have an opaque to transparent brown-pink apple jelly appearance on diascopy. Figure 52-11 Urticaria. Discrete and confluent edematous erythematous papules and plaques are characteristic of this whealing eruption. Wood s Light A Wood s lamp generates 360-nm ultraviolet or black light that can be used to aid the evaluation of certain skin disorders. For example a Wood s lamp will cause erythrasma a superficial intertriginous infection caused by Corynebacterium minutissimum to show a characteristic coral pink color and wounds colonized by Pseudomonas to appear pale blue. Tinea capitis caused by certain dermatophytes such as Microsporum canis or M. audouini exhibits a yellow fluorescence. Pigmented lesions of the epidermis such as freckles are accentuated while dermal pigment such as postinflammatory hyperpigmentation fades under a Wood s light. Vitiligo Fig. 52-12 appears totally white .

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