Comparison of Ex Vivo and In Vivo Dermoscopy in Dermatopathologic Evaluation of Skin Tumors.

IMPORTANCE: Ex vivo dermoscopy (EVD) can be a valuable tool in routine diagnostic dermatopathologic evaluation. OBJECTIVES: To compare in vivo dermoscopy (IVD) and EVD and to provide guidance for routine dermatopathologic evaluations. DESIGN, SETTING, AND PARTICIPANTS: This observational study collected 101 consecutive IVD and EVD images of skin tumors from a private dermatology practice from March 1 to September 30, 2013. Four observers (3 dermatologists and 1 dermatopathologist) blinded to the histopathologic diagnoses independently scored and compared the colors, structures, and vessels of EVD images with those of the corresponding IVD images. Data were analyzed from January 1 to March 31, 2014. MAIN OUTCOMES AND MEASURES: Concordance between the EVD and IVD images and gain or loss of colors, structures, and vessels on EVD relative to IVD images. RESULTS: The final analysis included 404 observations of 101 images. The EVD image was generally similar to the corresponding IVD image but clearly darker, with new areas of blue in 130 of 404 observations (32.2%) and white in 100 of 404 observations (24.8%) and loss of red in 283 of 404 observations (70.0%). Most structures were well preserved. New structureless areas were found in 78 of 404 observations of EVD images (19.3%), and new crystalline structures were detected in 68 of 404 observations of EVD images (16.8%). On EVD images, squames and crusts were lost in 56 of 404 observations (13.9%) and 43 of 404 observations (10.6%), respectively. Blood vessels were lost in 142 of 404 observations of EVD images (35.1%). CONCLUSIONS AND RELEVANCE: The EVD image is an important new tool in dermatopathology and may give direction to targeted tissue processing and examination of skin tumors.