JAMES M.GRICHNIKMD, PhD
Tinea versicolor (TV) is a superficial cutaneous mycosis that is caused by an overgrowth of Malassezia furfur, a dimorphic, lipophilic yeast that is present in normal skin (Figure 1). The pigmentation of TV lesions varies from white or light pink to dark brown (Figure 2). We demonstrate the “evoked scale sign” of TV, in which a visible layer of thin scale is elicited by either stretching or scraping the affected skin. Two techniques can be used to observe the evoked scale sign of TV. In the first technique, the clinician uses thumb and forefinger to stretch the skin, eliciting a visible white patch of scale overlying the affected area (Figure 3). On release, the scaly patch on the affected area is still recognizable (Figure 4). In the second technique, the clinician scrapes an active lesion with a No. 15 scalpel blade, which is held perpendicular to the skin to avoid laceration, or a glass microscope slide, again yielding a pale and fuzzy scale that is confined to the lesion (Figure 5).
Han A, Calcara DA, Stoecker WV, Daly J, Siegel DM, Shell A. Evoked Scale Sign of Tinea Versicolor. Arch Dermatol. 2009;145(9):1078. doi:10.1001/archdermatol.2009.203