You are in: eMedicine Specialties > Dermatology > TECHNOLOGY AND DERMATOLOGY DermoscopyArticle Last Updated: Jan 24, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Ignazio Stanganelli, MD, Director of Cutaneous Oncology, Niguarda Ca' Granda Hospital; Director, Skin Cancer Unit, Center for Cancer Prevention, Italy Coauthor(s): Maria Antonietta Pizzichetta, MD, Consulting Staff, Division of Preventive Oncology, Centro Di Riferimento Oncologico of Aviano, Italy Editors: Harold S Rabinovitz, MD, Clinical Professor, Department of Dermatology, University of Miami School of Medicine; Michael J Wells, MD, Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center; Amanda Oakley, MBChB, FRACP, Clinical Director, Clinical Associate Professor, Department of Dermatology, Waikato Hospital, Hamilton, New Zealand; Joel M Gelfand, MD, MSCE, Medical Director, Clinical Studies Unit, Assistant Professor, Department of Dermatology, Associate Scholar, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center Author and Editor Disclosure Synonyms and related keywords: dermatoscopy, epiluminescence microscopy, digital epiluminescence microscopy, videodermatoscope, dermatoscopy, epiluminescence microscopy, digital epiluminescence microscopy, videodermatoscope, video dermatoscope, video-dermatoscope, cutaneous malignant melanoma, pigmented skin lesions, malignant melanoma, skin cancer, skin cancer diagnosis, CMM, PSL, ELM, dermatologic color evaluation, skin lesion color evaluation INTRODUCTIONSection 2 of 11
  The widely used acronym ABCDE (asymmetry, irregular borders, multiple colors, diameter > 6 mm, enlarging lesion) contains the primary clinical criteria for diagnosing suspected cutaneous malignant melanoma (CMM). The early phase of malignant melanoma is difficult to identify because CMM can share many clinical features with an atypical nevus. Several studies have described diagnostic accuracy rates ranging from 50-75%, indicating a need for additional diagnostic tools. In the last 10 years, the introduction of dermoscopy, also termed epiluminescence microscopy (ELM), has opened a new dimension in the examination of pigmented skin lesions (PSLs) and, especially, in the identification of the early phase of CMM. Dermoscopy is a noninvasive method that allows the in vivo evaluation of colors and microstructures of the epidermis, the dermoepidermal junction, and the papillary dermis not visible to the naked eye. These structures are specifically correlated to histologic features. The identification of specific diagnostic patterns related to the distribution of colors and dermoscopy structures can better suggest a malignant or benign PSL. The use of this technique provides a valuable aid in diagnosing PSLs. Because of the complexity involved, this methodology is reserved for experienced clinicians. The equipment; technologic methods; diagnostic features; and primary aspects of melanoma, common nevi, atypical nevi, and other nonmelanocytic PSLs are discussed in this article. TECHNICAL PROCEDURES AND EQUIPMENTSection 3 of 11
Dermoscopy involves an evaluation of the skin surface. During a dermoscopy assessment, the PSL is covered with a liquid (usually oil or alcohol) and examined under a specific optical system (see Images 1-4). Applying oil reduces the reflectivity of the skin and enhances the transparency of the stratum corneum. This allows visualization of specific structures related to the epidermis, the dermoepidermal junction, and the papillary dermis, and it also suggests the location and distribution of melanin. DermatoscopeThe dermatoscope (see Image 1) is the simplest and best-recognized piece of equipment used to perform a dermoscopy examination. It is similar to an otoscope, is user friendly, and is inexpensive. This optical system's features include monocular observation, magnification X10, and the use of an illumination system (3.5-V halogen lamp). StereomicroscopeAnother optical instrument, the stereomicroscope (see Image 1), allows an accurate binocular observation with different magnifications (X6-80). The illumination system includes a halogen lamp (12 V/50 W). The stereomicroscope is expensive, is large and bulky, and is only available in a few centers. From an empiric point of view, visualization is better than with the dermatoscope, but formal studies of the differences in diagnostic features and accuracy of the 2 instruments have never been published. VideodermatoscopeFeatures of another optical system, the videodermatoscope (see Image 2), include a video probe that transmits images of the PSL to a color monitor. The recent addition of a digital system to the stereomicroscope, also termed the digital epiluminescence microscope (see Image 3), and/or to the videodermatoscope has opened a new area of development with the advantages of computerized technology. However, the technologic features (which are cost dependent) of the camera (single-chip video charge-coupled device, 3-chip charge-coupled device, or still digital; see Image 4), optical system, monitor, digitized board, and software can influence the resolution and quality of the images. These features can strongly influence the evaluation of a PSL; a low-resolution instrument may prevent accurate diagnosis. COLORSection 4 of 11
Accurate evaluations of the color of a PSL, the degree of pigmentation, and the distribution of the colors within the lesion are the most important elements of a dermoscopy examination. The epidermis usually appears white, but acanthosis results in a grayish-brown or brownish-yellow color. Melanin is the most important pigment in determining different structural and chromatic patterns. The PSL can have a different degree and distribution of pigmentation depending on the location of melanin in different layers of the skin. Melanin location and lesion color
Other possible colors include various shades of white and red. White shades are related to regression and may be seen with melanomas, benign melanocytic nevi (halo nevus), and nonmelanocytic lesions (lichenoid keratosis, scars). Red shades are related to increased vascularization in tumors, an increased number of capillary vessels, and bleeding within the lesion. If bleeding persists and crust develops, the color ranges from red-black to blue-black. A good evaluation of colors and their relative distribution is essential for achieving the correct clinical diagnosis of a PSL. GUIDE CRITERIASection 5 of 11
ELM features can be divided into primary and secondary guide criteria, which show numerous different manifestations related to chromatic and geometric variables (eg, distribution, width, caliber); these are discussed in detail in the description of each ELM feature. Primary criteriaPigment network The most important ELM feature of melanocytic lesions is the pigment network (PN), which consists of pigmented network lines and hypopigmented holes. This feature is correlated histologically to the length of the rete ridges and to the distribution of melanin within the keratinocytes of the epidermal rete ridges. The network of hypopigmented holes corresponds to the suprapapillary plate, which is relatively thin and contains less melanin. The network lines correspond to the rete ridges, which are thicker and have a greater quantity of melanin. In melanocytic nevi, the PN is slightly pigmented. Light-brown network lines are thin and fade gradually at the periphery. Holes are regular and narrow (see Images 5-9). The distribution is symmetric and sometimes accentuated in the center of the lesion (see Images 10-13). In melanoma, the PN usually ends abruptly at the periphery and has irregular holes, thickened and darkened network lines, and treelike branching at the periphery (see Image 14). In CMM, the PN features change between bordering regions. Some areas of malignant lesions manifest as a broad and prominent PN, while others have a discrete irregular PN. The PN also may be absent in some areas (see Image 15). Atypical nevi (dysplastic nevi) are difficult to diagnose at times because they may show areas of irregular and discrete PN distributed asymmetrically (see Image 16). Pseudopigmented network ELM features of homogeneous pigmentation of the face (interrupted by hypopigmented hair follicles and hypopigmented sweat gland openings) create a pseudopigmented network. In benign lesions, this pseudonetwork tends to be uniform and symmetric in color and pattern (see Images 17-18). In contrast, in lentigo maligna (see Image 19) and lentigo maligna melanoma, the pseudonetwork becomes nonuniform and asymmetric in color and pattern because of the increased number of atypical melanocytes extending down hair follicles and adnexal structures. The meshes become broader, and the holes are larger. Radial streaming and pseudopods Radial streaming and pseudopods are different morphologic expressions of malignant melanoma, specifically melanoma in the radial growth phase. Radial streaming (see Image 20) is a linear extension of pigment at the periphery of a lesion, often appearing in groups of nearly parallel, radially arranged linear structures. Depth determines the colors, which are brown, dark brown, blue-gray, and black. Pseudopods (see Image 21) are curved fingerlike projections that are predominantly dark brown or black and are located at the periphery of a lesion. They occasionally have small knobs at their tips. Radial streaming and pseudopods histologically correspond to confluent junctional nests of atypical melanocytes. Pigmented globules Pigmented globules are round or oval, dark brown or black, and larger than 1 mm in diameter. They are uniform in PSLs but vary in size, color, and shape in atypical nevi and melanoma. When abundant, aggregated globules have a cobblestone pattern (see Images 22-23), which is typical of benign melanocytic lesions (see Images 22-25). In CMM, globules are dark or slate blue and are distributed irregularly (see Image 26). Occasionally, isolated dark globules are seen at the margins of an achromic lesion; in this case, a diagnosis of melanoma is suggested. Pigmented globules correspond histologically to nests of pigmented melanocytes (nevus or melanoma) at the junction in the papillary dermis or, because of melanin storage, in melanophage clusters in the papillary dermis. Milky-red globules can be seen in CMM, representing melanoma cell nests with increased vascularization. Secondary criteriaPigmented dots Pigmented dots are small, round or irregularly shaped pinpoint structures that are black or dark brown. They correspond to focal accumulations of free melanin or an increased number of highly pigmented melanocytes in the cornified layers of the epidermis. The presence of melanophages and/or atypical melanocytes in the dermis correlates with blue-gray or slate blue dots and is typically found in pigmented melanocytic and nonmelanocytic lesions undergoing regression. Vertical capillaries found on apical dermal papillae appear as red dots on the palms and soles; sweat gland openings appear as white dots. In benign melanocytic lesions, dots in the center of the lesion are homogeneous in color and are regular in size, shape, and distribution (see Image 27). In CMM or in atypical lesions, dots may occur at the periphery of the lesion and are irregular in size, shape, and distribution (see Image 28). Blue-white veil A blue-white veil is a ground-glass area of pigmentation that is blue-gray to blue-white in color. This ELM feature is present in homogeneously pigmented black or dark brown lesions and is associated with thickening of the epidermis (see Images 28-29). It is correlated histologically with compact orthokeratosis and hypergranulosis, with confluent nests of heavily pigmented melanocytes in the dermis. A blue-white veil is often found in melanomas (see Image 14, Images 20-21, Image 28) and Spitz nevi (see Image 29). Blue-gray areas Blue-gray areas are ELM features with coloration varying from gray-blue to deep gray. Blue-gray or bluish areas may be either isolated disseminated granules or peppering and ill-defined spots with bizarre margins (see Image 30). They may be associated with melanoma regression. They are correlated histologically with the presence of melanin and/or hemosiderin within melanocytes and melanophages, and blue-gray areas may be free in the papillary and middle dermis. Steel blue areas Steel blue areas are structureless, gray-blue, and homogeneously diffuse. They are found in blue nevi (see Image 31) and occasionally are associated with globules, dots, or both. A central steel blue area may be found in some combined blue nevi. Depigmentation Depigmentation depends on a lack or reduction of pigment in the PSL. With depigmentation, differentiation can occur in hypopigmented regions that correspond to pigmented areas lighter than other areas within the nevus (see Image 32). Differentiation also can occur in white areas that correspond to well-defined white (see Image 28) or milky red-white areas (see Image 33). In contrast to hypopigmented areas, depigmented areas completely lack pigment. Histologically, they correspond to fibroplasia, telangiectasias, and loss of melanin. NONSPECIFIC GUIDE CRITERIASection 6 of 11
Milialike cystsMilialike cysts are small, circular, whitish-yellow areas with sizes ranging from 0.1-1 mm (see Image 34). They are important for the diagnosis of seborrheic keratosis but can also be found in papillary melanocytic nevi and melanoma, although in seborrheic keratosis, they are larger. Histologically, milialike cysts correspond to keratin-filled cysts. Comedolike openingsComedolike openings are another typical diagnostic feature of seborrheic keratosis. They are keratin-filled porelike openings that communicate with the surface of the lesion. They appear yellow-brown, with a circular or oval shape and a light round halo (see Images 34-35). They are correlated histologically with keratin within the invaginations of the epidermis. Red-black lagoonsRed-black lagoons are the pathognomonic diagnostic criteria of hemangioma and angiokeratomas. They are small, well-defined, oval or round areas that range from blue-red to blue-black (see Image 36). Histologically, they correspond to large lagoons and thrombi within the vascular spaces of papillary dermis. Subungual hemorrhages can have blue-red and/or red-black homogeneous pigmentation without vascular lagoons (see Image 37). Maple leaf–like pigmentationsMaple leaf–like pigmentation, an important diagnostic criterion for basal cell carcinoma, is gray-brown to gray-black with a shape similar to that of a maple leaf or to the fingers of a hand (see Image 38). Histologically, they correspond to heavily pigmented basaloid cells within the nest of basal cell carcinoma. VASCULAR PATTERNSSection 7 of 11
Vascular patterns are important markers for melanocytic and nonmelanocytic lesions. The vascular pattern can be evaluated more accurately using magnification of higher than 10X. Kreusch and Koch described the main vascular patterns as follows:
OVERVIEW OF DIFFERENT DERMOSCOPIC DIAGNOSTIC PROCEDURESSection 8 of 11
The different technical instruments and the guidelines for dermoscopy diagnosis for PSLs are described in Guide Criteria and Technical Procedures and Equipment, respectively. This section describes the different methods of classification and diagnosis using dermoscopy that have been developed in the last several years. In the world of dermatology, ELM recognition of suggestive melanomas is based on the observation of numerous parameters; not just one of these factors is specific for melanoma. The literature shows that many different methods of classification are used for dermoscopy. The most widely used ELM procedures are pattern analysis, the ABCD dermoscopy rule, the Menzies methods, the 7-point checklist, and the stratification of risk level. Pattern analysisDescribed by Pehamberger et al and recently redefined by the Consensus Net Meeting on Dermoscopy (CNMD), pattern analysis is the procedure most used by dermatologists. Its efficiency is correlated to the experience of the observer. Pattern analysis uses a process of diagnostic framing that keeps control of the known analytic data of all the dermatoscopic parameters of PSLs and of the prevalence of single variables. That is, it helps determine if the PN is present or absent, and, if the PN is present, if it is regular or irregular and delicate or prominent, among other variables discussed earlier. The various types of PSLs, and specifically differentiation between benign and malignant melanocytic lesions, can be determined through pattern analysis of specific dermatoscopic features. The 2 steps in the new process of pattern analysis are (1) deciding whether the lesion is melanocytic or nonmelanocytic and (2) identifying the melanocytic lesion, making a diagnosis, and planning relative management. Pattern analysis has been deemed superior to the other algorithms (ie, ABCD dermoscopy rule, Menzies method, 7-point checklist) for diagnostic efficiency by experts all over the world in the 2000 CNMD. Pattern analysis - Step 1 The first step to identifying a melanocytic lesion is to look for the presence of aggregated globules (see Images 22-23), PN (see Images 5-8 and Image 16), or branched streaks (ie, fragmented irregular PN) (see Images 14-15). If the above patterns are absent, other characteristics should be sought (substeps). First, note that a typical marker for blue nevus is the presence of homogeneous steel blue areas (see Image 31). Second, the lesion should be evaluated for the presence of moth-eaten borders, fingerprinting, comedolike openings, and milialike cysts. In this case, the lesion is suggestive of either a solar lentigo (see Image 18) or a seborrheic keratosis (see Image 34). Third, if red or red-blue to black lagoons are present, the lesion should be considered a hemangioma (see Image 36) or an angiokeratoma. Finally, the lesion should be evaluated for maple leaf–like structures, arborizing telangiectasias, spoke-wheel–like areas, andgray-blue ovoid nests. This lesion is compatible with a basal cell carcinoma (see Image 38). All lesions should be reevaluated to determine if they have a melanocytic structure, even if they do not have the structures described above. Pattern analysis - Step 2 The main goal for step 2 is to make an accurate differential diagnosis between benign melanocytic lesions and melanomas. The important features in distinguishing these 2 groups are the overall general appearance of color, architectural order, symmetry of pattern, and homogeneity, known by the acronym CASH. Melanocytic nevi have few colors, a regular design, and symmetrical patterns (see Image 5, Image 10, Image 12, Images 16-17, Image 22, Image 24, and Image 31). In contrast, malignant melanoma often has several colors, architectural disorder, asymmetrical patterns, and heterogeneity (see Images 14-15, Image 21,
Menzies scoring method Menzies scoring method is another effort to simplify the pattern analysis ELM system. This classification identifies 2 negative aspects and 9 positive aspects commonly used in the semeiotics of dermoscopy. To make a diagnosis of melanoma, 2 negative aspects (negative features) must be absent from the lesion and 1 or 2 positive aspects (from 1 of the 9 positive features) must be present.
The 7-point checklist Developed by Argenziano et al in 1998, the 7-point checklist is another variation of the qualitative pattern analysis system, but with a point system. This method uses 7 criteria specific for melanoma. It includes 3 major criteria, to each of which is attributed 2 points, and 4 minor criteria, to each of which is attributed 1 point (see Images 53-54). This method has fewer criteria to identify and analyze compared with the pattern analysis method. A score of 3 or greater has a high sensitivity of being melanoma.
Stratification of risk level Described by Kenet and Fitzpatrick in 1994 and recently revised by the Melanoma Cooperative Group, this methodology seems to provide very simple and standardized management of both the diagnosis and therapy of early melanomas and suggestive melanocytic lesions. The stratification of risk level is the basis for the management of melanocytic pigmented lesions. This classification system is based on a wide database of 61,000 examined cutaneous lesions, with 478 diagnosed as cutaneous melanomas (62% stage I, per the American Joint Committee on Cancer). It has 5 risk levels essentially correlated to the history (as described by the patient) and clinical course of the lesion, the presence or absence of a PN, the different variables of the PN associated with the lesion, and other ELM structures (see Images 55-56). The stratification risk level includes the following 3 integrated steps:
The Melanoma Cooperative Group emphasizes that anamnesis, clinical observation, and other additional parameters be integrated into dermoscopy evaluations for the stratification of risk level in order to standardize the management of melanocytic lesions. Practical approach to the management of a PSLThe different dermoscopy classifications have their own worthy internal coherence; however, the use of the different diagnostic scores can be affected by interobserver and intraobserver variability when only a single guideline is used for evaluation (ie, limited qualitative and quantitative agreement). Furthermore, all of these classifications can prove to be very sensitive but not very specific; thus, they do not allow 100% accuracy. Although very useful to detect intraepidermal lesions, dermoscopy is limited in regard to nodular lesions or clearly dermal lesions, lesions without pigmentation, very dark lesions in which the amount of pigment does not allow the observation of ELM signs, and faintly pigmented seborrhoic warts. The efficiency of dermoscopy is closely related to an integrated diagnostic synopsis for trained clinicians. The user must think in global diagnostic terms when considering the accuracy of dermoscopy findings, independent of the methods used; a broader aim is to include case histories and clinical assessment. In fact, the first steps to be integrated by dermatoscopic evaluation are as follows:
Such a combination of the traditional clinical diagnostic procedures and dermoscopy allows better classification of suggestive melanocytic lesions. HOT TOPICS IN DERMOSCOPYSection 9 of 11
Amelanotic melanoma Amelanotic malignant melanoma is a subtype of cutaneous melanoma with little or no pigment at visual inspection. A review of the literature indicates that amelanotic melanomas represent 2-8% of all malignant melanomas; the precise incidence is difficult to calculate because the term amelanotic is often used to indicate melanomas only partially devoid of pigment. Truly amelanotic melanomas are rare; often some pigmentation is present at the periphery of the lesion, and they may mimic benign and malignant variants of both melanocytic and non-melanocytic lesions. According to the extent of the hypopigmentation, amelanotic melanoma can be classified as follows (1) truly amelanotic melanoma, lacking any trace of melanin even if viewed under dermoscopy; (2) partially pigmented melanoma, with larger or smaller pigmented sections covering up to 30% of its total surface; (3) hypomelanotic melanoma, showing a faint brownish tan with little variation of its intensity, which can occupy more than 30% of its total surface and may cover the entire area. Amelanotic malignant melanoma tends to occur in sun-exposed skin, especially in elderly persons with photodamage, and may appear as erythematous, sometimes scaly, macules or plaques with irregular borders, simulating benign inflammatory plaques, superficial basal cell carcinoma, actinic keratosis, Paget disease, or Bowen disease. It may also manifest as translucent papules, thereby resembling basal cell carcinoma, or it may clinically resemble keratoacanthoma or Merkel cell carcinoma. Alternatively, it may manifest as an exophytic nodule, often eroded, simulating a pyogenic granuloma or hemangioma, or as a skin-colored dermal plaque/nodule known as desmoplastic malignant melanoma. From a dermoscopic point of view, amelanotic melanoma lacks most of the dermoscopic criteria reflecting pigmentation, and the vascular structures are frequently the only clue for its diagnosis. The vascular patterns associated to amelanotic melanoma include milky-red globules/areas of dotted or linear irregular or polymorphous vessels (ie, a combination of dotted and linear irregular vessels; see Images 40-41). In addition, irregular hairpinlike or glomerular vessels can also be found in amelanotic melanoma, albeit less frequently. Because dermoscopy uses criteria reflecting pigmentation and vascular patterns, it is a useful technique for pigmented melanoma and for amelanotic melanoma. However, the vascular patterns can suggest a diagnosis of melanoma when associated with other criteria found in melanocytic lesions, such as pigment network, irregular pigmentation, streaks, irregular dots/globules, regression structures, and a blue-whitish veil. In truly amelanotic melanoma, vascular patterns alone may not be sufficient to diagnose melanoma because hairpin vessels, dotted areas, and even milky-red areas have also been found in seborrheic keratosis and common nevi, respectively, and in melanomas. MULTIMEDIASection 10 of 11
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