ABSTRACT
Reflectance confocal microscopy (RCM) of TE and DTE identifies many of the features seen on histology. Mosaic images at the level of the dermis show a lesion composed of islands of tumor ramified by brightly refractile coarse collagen arranged in parallel bundles ( Figures 5.4 , 5.16 ). On RCM, TE shows tumor islands with knobby extensions composed of small, round, nucleated cells ( Figures 5.6 , 5.8 ). Variable peripheral palisading of brighter basaloid cells with oval nuclei, reminiscent of basal cell carcinoma, is identified ( Figure 5.10 ). Tumor islands are wrapped in a brightly refractile stroma ( Figure 5.8 ). Corresponding histology shows basaloid tumor cells arranged in islands ( Figure 5.5 ) with branching nests and abortive hair follicle formation within a fibrotic stroma ( Figure 5.3 ). This characteristic fibrotic stroma concentrically encases tumor islands in parallel bands, creating an ‘onion skin’ appearance ( Figure 5.7 ). Occasionally, peripheral palisading of basaloid cells, mimicking basal cell carcinoma, is identified ( Figure 5.9 ). 5,7 DTE shows similar features to TE, but has much smaller tumor cell nests and cords scattered within more abundant, brightly refractile stroma, corresponding to the histologic findings of small basaloid nests and cords tightly embedded in a sclerotic stroma ( Figures 5.15-5.20 ). 5 Both TE and DTE show some tumor islands containing round black spaces filled with brightly refractile material, corresponding to tricholemmal horn cysts on histology ( Figures 5.11, 5.12 , 5.15-5.20 ). 4,5
Figures 5.1, 5.2 Clinical photograph of a 3 mm, skin-colored, firm, papule on the central forehead of a 60-year-old woman with multiple familial trichoepithelioma. Dermoscopic photograph shows a lesion with a milk-white hue and a few telangiectatic surface vessels. Reproduced with permission of S. Karger AG, based from Ardigo M , Zieff J , Scope A et al. Dermoscopic and reflectance confocal microscope findings of trichoepithelioma . Dermatology 2007; 215:354-8.
