Differences between histologic and dermoscopic criteria
Histopathologic evaluation is performed on vertical sections of tissue, thus allowing the assessment of the full depth of the lesion from scanning magnification to a cellular-level magnification, however it directly assesses less than 2% of the lesion.
Since histopathology is based on paraffin embedded tissue, an additional advantage is the use of special stains and immunohistochemical techniques (e.g. MelanA, S100, HMB45 etc.) that may assist in diagnosis.
Dermoscopy, on the other hand, is performed based on a horizontal view of the entire lesion, but is generally limited in depth to the papillary dermis. Dermoscopy allows the observer to dentify “colors” and “structures” that are not perceived by the unaided eye. These colors and structures are two-dimensional surface projections of tissue structures (e.g., melanocytic nests or blood vessels). Aside from assessing the entire horizontal plane of the lesion, dermoscopy has two other major advantages: (1) the dermoscopist is able to examine additional lesions on the patient's skin, and integrate these findings; (2) dermoscopy allows the follow up of lesions. This provides important information regarding the lesion’s biology and dynamics.