Tips and tricks in the dermoscopy of pigmented lesions
© Kaminska-Winciorek and Spiewak; licensee BioMed Central Ltd. 2012
Received: 29 November 2011
Accepted: 16 July 2012
Published: 24 August 2012
Dermoscopy is a useful, widely used tool for examining pigmented lesions, especially helpful in cases of an uncertain nature. Nevertheless, doctors may experience diagnostic difficulties while using this method. An example of this may be found in the examination of subcorneal hematoma, dark nevi with black lamella or lesions of acral volar skin. In such cases, a few diagnostic tricks have proven to be helpful in achieving diagnostic accuracy.
This paper reviews various methods of performing dermoscopy, suggesting a number of simple, yet helpful tests. These include the adhesive tape test, the skin scraping test and the ink furrow test. The adhesive tape test is helpful in differentiating between dark melanocytic nevi and melanoma. Hematoma may be more easily differentiated with the use of the so-called skin scraping test. The confirmation of benign and melanocytic lesions of acral volar skin, on the other hand, is more accurate when using the ink furrow test. These methods have been discussed here based upon a series of literature reviews, the authors’ own experience and, also, iconography.
The present article describes novel methods used in dermoscopy, helping to bring about a faster, more accurate diagnostics of those lesions which have proven to be more difficult to recognize. Helpful tricks, such as have been known to professional literature, as well as the authors’ own experience (for instance, applying urea cream to hyperkeratotic lesions or using photographs of skin lesions taken with the aid of a mobile phone camera – all prior to surgery) will surely be considered beneficial to the practitioner, be it dermatologist or any other physician.
Dermoscopy (synonyms include terms such as epiluminescence microscopy, skin surface microscopy, incident-light microscopy) has, of late, made a name for itself as a greatly appreciated method of dermatological diagnosis. Initially intended for the differential diagnosis of pigmented lesions, dermoscopy became more widespread in the 1990s. To the present day, dermoscopy is used in assessing inflammatory dermatoses (inflammoscopy), parasitic invasions (the so-called “entomodermoscopic method”) and in cases of scalp disorders (trichoscopy) - all in the follow-up to dermatological treatment.
Performing dermoscopy during dermatological examination should really be adapted as a routine activity. Although a complete and thorough examination of the skin (CSE) with the use of a dermoscope is, effectively, more time-consuming, it is strongly advisable to dedicate the incurring three or four additional minutes (compared to a traditional dermatological examination without the use of dermoscopy) to increase the detection sensitivity of potentially fatal skin malignancies. Dermoscopy may be carried out with the aid of classic dermoscopes, stereomicroscopes, dermoscopes connected to a digital camera, or even videodermoscopes - in which an image obtained through a video camera is sent to a computer screen. At present, technologically advanced, high resolution digital cameras, built into videodermoscopes, considerably improve image resolution and enhance the quality of the obtained images. Moreover, the development of special dermoscopic extensions allows for the conversion of top-end mobile phones into pocket dermoscopes. This provides an opportunity for a quick analysis of the image, transferring the photo via MMS and email and thus creating a type of ‘handheld’ patient database.
The article describes a number of practical dermoscopic methods which can be implemented in order to achieve a faster and more accurate diagnostics of lesions which have proven to be difficult to recognize. Professional literature has played host to many of these over the years, yet the authors have no doubt that the methods described here (all based on their own medical experience) shall be appreciated by dermatologists and general practitioners alike. We have described these useful tricks and tips based on literature review and our own work with dermoscopic figures. Written consent has also been obtained from the patients for the publication of the accompanying data as well as any associated images. A copy of this written consent is available for review at the discretion of this journal’s Series Editor.
Results and discussion
Types of dermoscopic devices
The majority of doctors who perform dermoscopy begin their evaluation of melanocytic nevi with manual dermoscopes, which allows for the direct visual inspection of the lesion and helps in avoiding possible distortions of colour, structures and edges of the lesion in question – all while transmitting this data to a computer. Research conducted by Seidenari et al. confirmed that the type of equipment used does not influence the identification of specific dermoscopic features. However, smaller magnifications used for archiving the lesions may decrease the quality of images.
Immersion in non-polarized light or evaluation in polarized light?
Nowadays, polarized light dermoscopes in which immersion is not required are becoming more and more popular. Dermoscopic structures such as milia-like pseudocysts, comedo-like openings, bluish-grey homogenous areas, peppering-like, white-bluish structures with regression and brightly-coloured areas - all these can now be better visualized as compared to detection and revision with the use of non-polarized dermoscopes. The latter ones, it must however be said, are effectively better in assessing vascular structures and red areas. Non-polarized dermatoscopes are also more effective in showing pigmented lesions (increased melanin deposition), and blue nevi[4, 5]. In order to combine the benefits of both types, dermoscopes with dual light-sources (non-polarized and polarized) have now been designed. In some cases, the dermoscope is used without immersion (so-called dry dermoscopy), for example in assessing the skin of the scalp, vellus or terminal hair, or in the case of examining dermatoglyphs or sweat glands in the palms and feet.
Inspection of all lesions or only those “ugly ducklings”?
A common mistake is to limit dermoscopic assessment only to lesions clinically suspicious or pointed out by a patient as an “ugly duckling”. Although the “ugly duckling” is usually a sign typical of melanoma, all existing melanocytic lesions must undergo dermoscopic evaluation, regardless of their location and size. According to Bono et al. melanomas are more frequently diagnosed among minor melanocytic lesions (less than 3 mm in size) than among those of greater diameter, which usually spark more concern among patients[8, 9]. So-called “micromelanomas” in the form of foci measuring less than 3 mm in diameter constituted 2.4% of all examined melanomas (22 of 924 cases of primary foci of melanoma). In a further study using the same test group, melanoma was diagnosed in as many as 23 of 206 pigmented lesions of a diameter less than 3 mm. Compared to a clinical examination of pigmented lesions smaller than 3 mm in diameter (sensitivity for the detection of melanoma 43%, specificity 91%), dermoscopy shows a much higher sensitivity for the diagnosis of melanoma (83%) and lower specificity (69%) than clinical examination.
The classification of atypical nevi proposed in 2009 by Marghoob et al. includes patterns of melanocytic nevi of the “Beauty and the Beast” type, emphasizing the assessment of overall symmetry of colour and form as a means of distinguishing benign (also dysplastic) nevi from melanoma. Melanomas can display one of the “Beast” structures such as anatypical network, globules and dots, streaks (radial streaming or pseudopods), eccentric blotches, a blue-white veil, a negative pigmented-network, regression structures and abnormal vascular formations. Among atypical nevi of the “Beauty” type, cases of the so-called “wolf in sheep’s clothing” have been observed, where a seemingly benign nevus in fact proves to be a melanoma.
The “4 × 4 × 6 rule” postulated by Zalaudek et al. is meant to support the clinicians’ memorisation of basic dermoscopic patterns of nevi, along with all other factors influencing specific dermoscopic patterns. Four dermoscopic criteria affect the evaluation of melanocytic nevi. These are: colour (black, brown, blue, grey), pattern (globular, reticular, starburst and homogeneous blue), distribution of pigment (multifocal, central, excentric and uniform) and specific location (face, acral volar skin, nail plate, mucous membrane) and 6 factors affecting the dermoscopic pattern (age, skin phototype, medical history of melanoma, UV exposure, pregnancy and dynamics of growth). It is not only the dermoscopic pattern, but also the circumstances and factors influencing its formation and evolution that determine proper therapeutic management. These factors have been discussed in detail in a recent paper by Zalaudek et al.. In the dermoscopic assessment of melanocytic nevi, the dermoscopic pattern is often related to the patient’s age, as well as the location and duration of the nevus. Among children younger than 11 years of age, the globular pattern is most common, especially on the trunk, while the reticular pattern can more often than not be found on the extremities. In the case of patients above 15 years of age, reticular and homogeneous patterns prevail. Thus, the reticular pattern, typical for junctional nevi usually induced by exogenous factors such as exposure to UV radiation, is more often observed on sun-exposed areas.
Additional dermoscopic tests
The adhesive tape test
The “ugly duckling sign” and black lamella
The ink furrow test
Diagnosis of acrally located pigmented lesions
The parallel furrow pattern: a darker colour runs along the sulci; this is the most common pattern of acrally located benign melanocytic lesions (Figure 4),
The fibrillar pattern: the pigment is distributed along numerous fine lines which cross the sulci
The lattice-like pattern: this is characterized by the presence of bands of pigment, distributed parallel and transverse to the sulci
The non-typical pattern: one in which no characteristic features can be defined; this type however, is not equivalent to the so-called multicomponent pattern
Melanocytic nevi showing the parallel furrow or fibrillar pattern are predominantly located on the foot, in which case a regular parallel distribution of skin markings is observed. However, as a rule, these nevi rarely affect the arch of the foot. Additionally, the fibrillar pattern of melanocytic nevi indicates a predilection for the load bearing areas of the foot. The lattice-like pattern is mainly found on the arch area of the foot.
Other patterns have also been recognized, among them the parallel ridge pattern – in which the pigment is arranged along the crista, as opposed to the parallel furrow pattern. The parallel ridge pattern is mainly to be found in melanoma in situ or in the early stages of invasive acral volar skin melanoma. The parallel ridge pattern shows a high specificity (99%) in the detection of melanoma of acral volar skin, especially in its early stages. Among less common patterns, there is also the globular pattern – in which pigmented globules present a regular distribution inside the nevus. Apart from this, there is also the homogeneous pattern in which a homogeneous area of light-brown to dark-brown colour is predominant with blue pigmentation, and the reticular pattern, which is similar to a basic reticular pattern typical of melanocytic nevi and ranging from light-brown to dark-brown colour. The transitional pattern combines a brown to dark-brown pigment network with a parallel orientation of pigment bands. In clinical trials, the most common pattern of acral melanocytic nevi was the parallel pattern (42-50%), lattice-like pattern (12-15%), the reticular pattern (15-20%) and atypical pattern (ranging from 10-13% up to 65% of all investigated melanocytic nevi)[17, 18]. Other patterns of melanocytic nevi observed included the fibrillar (10-38%), homogeneous (9-13%), globular (5-20%) and reticular pattern (2-40%)[17, 18]. The transitional pattern had been noted in 1.8% of cases.
The scraping test in diagnosing lesions of parallel ridge pattern
Hematoma or melanoma?
Kaminska-Winciorek G and Spiewak R: 1) have made substantial contributions to concept and design, acquisition of data, analysis and interpretation of data; 2) have been involved in drafting the manuscript or revising it critically for important intellectual content; and 3) have given final approval of the version to be published. This publication was financed in part from the Jagiellonian University grant K/ZDS/001906.
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