Dermoscopy
The differential diagnosis of pigmented skin lesions usually poses significant diagnostic and management challenges for dermatologists considering the risk of skin neoplasms, such as malignant melanoma (MM) and basal cell carcinoma (BCC).The dermatological examination of pigmented lesions includes detection and interpretation of many gross morphological features (size, shape, color and three-dimensional changes). Most lesions can be easily diagnosed by experienced dermatologists with unaided eyes. However, for those pigmented lesions that are clinically suspicious for MM and BCC, dermoscopy holds great promise because it can improve sensitivity of clinical examination. It does not replace histopathological examination.
Dermoscopy is a non-invasive method and many different terms have been used to describe this technique, such as “dermatoscopy” (Saphier J., 1920), “incident light microscopy” (Fritsch P. et al., 1981), “epiluminescence light microscopy” (Pehamberger H., 1987) and “surface microscopy” (Soyer H., 1989). In 1991, the term “dermoscopy” was introduced by Friedman RJ. et al. and is currently used in USA.
This technique should be understood as a combination of magnifying glass with a transilluminating light source that enables the observer recognizing the dermal-epidermal and dermal structures. By using naked-eye inspection or even under optical magnification, most of the light is reflected from the skin surface and therefore, subsurface elements are not visible, limiting clues for correct diagnosis. The dermoscopic principle to avoid light reflection is the use of an immersion liquid or light polarization.
The colors and structures observed under dermoscopy are the final result of the amount and location of melanin (stratum corneum, epidermis, papillary and deeper dermis), blood vessels, keratinocytes and fibrosis. To make the differential diagnosis, the observer has first to decide whether the lesion is of melanocytic or non-melanocytic origin; second, characterize the lesion as benign, suspect or malignant.
Dermoscopy is performed using hand-held, stereomicroscopes or electronic dermoscopes. The hand-held devices are less expensive and easier to use but storage of images for accurate follow-up is not possible. Some hand-held models are equipped with adapters for digital cameras that allow taking clinical as well as dermoscopic photographs with high image quality.
Dermaimaging.com is a site dedicated to dermoscopy, where melanocytic and non-melanocytic lesions are discussed based on the visible structures observed. Some lesions are presented together with their histological result and others with dermoscopic features that favor a specific diagnosis.
Recommended Bibliography:
-Marghoob AA, Braun RP, Kopf AW. Atlas of Dermoscopy. United Kingdom: Taylor & Francis Group, 2005
-Cabrera H, Garcia S. Nevos. Buenos Aires/Argentina: Actualizaciones médicas
-Johr R, Soyer HP, Argenziano G, Hofmann-Wellenhof R, Scalvenzi M. Dermatoscopia-Pautas de diagnóstico. Madri/España. Marbán Libros, S.L., 2007
-Cabo H, Argenziano G, Carlos B, Cohen Sabban E, Kittler H, Kowalczuk A, Malvehy J, Marghoob A, Peris K, Piccolo D, Puig S, Soyer P, Stengel F, Stolz W, Thomas L, Zalaudek I. Dermatoscopía. Buenos Aires/Argentina: Ediciones Journal, 2008
-Tosti A. Dermoscopy of Hair and Scalp Disorders.United Kingdom: Informa Healthcare, 2007
-Rezze GG, Soares de Sá B, Neves RI. Atlas de Dermatoscopía Aplicada. Sao Paulo: Editora Martinari, 2008
-Carroll D, Billingsley E, Helm K. Diagnostic Basal Cell Carcinoma by dermoscopy. 1998. J Cutaneous Medicine and Surgery 3: 62-67
-Giacomel J, Zalaudek I. Dermoscopy of superficial basal cell carcinoma. 2005. Dermatol Surg 31: 1710-1711
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