The dermatoscopic ABCD rule does not improve diagnostic accuracy of malignant melanoma

The dermatoscopic ABCD rule has been suggested to improve diagnostic performance regarding cutaneous malignant melanoma. Using this rule, a total dermatoscopy score is calculated from the presence of various dermatoscopic elements. A total dermatoscopy score above 4.75 signifies possible and 5.45 probable melanoma. We compared the diagnostic accuracy of dermatoscopy with and without the use of the ABCD rule. Furthermore, receiver operating characteristic analysis was performed for the ABCD rule. The area under the receiver operating characteristic curve was 0.854 (range 0.777-0.906) demonstrating that in 85.4% of the cases, cutaneous malignant melanomas were rated higher than the non-melanoma skin lesions. Sensitivity for the melanoma diagnosis was higher for simple dermatoscopy than when the ABCD rule was used (p<0.05). There was no difference in specificity when a total dermatoscopy score of 4.75 was used as cut-off point, but specificity was lower for simple dermatoscopy than when the total dermatoscopy score of 5.45 was used. Diagnostic accuracy was higher for simple dermatoscopy than for the ABCD rule (p<0.01). In conclusion, the dermatoscopic ABCD rule was not superior to simple dermatoscopy, and fewer malignant melanomas were identified with this rule.     

Preoperative assessment of melanoma thickness by ABCD score of dermatoscopy

BACKGROUND: Epiluminescence microscopy is a useful tool for the noninvasive diagnosis of malignant melanoma based on criteria that have been correlated with specific histologic characteristics. Previous studies have also shown a good correlation between the frequency of some dermatoscopic criteria based on pattern analysis (pigment network, blue-gray areas, vascular pattern) and tumor thickness. This technique could be useful in the preoperative assessment of tumor thickness as an indication for sentinel node biopsy. OBJECTIVE: Our purpose was to evaluate the possible role of the total dermatoscopy score (TDS) assigned to a series of lesions in accordance with the ABCD rule of dermatoscopy as a preoperative predictor of melanoma thickness. METHODS: For 84 cutaneous melanomas (17 were in situ melanomas; 67 invasive cases with mean thickness 0. 93 mm; range, 0.2-3.9 mm; standard deviation, 0.63) consecutively excised at the Department of Dermatology of Florence, TDS was established by two observers blinded as to the tumor thickness. The performance of different cut-off points of TDS in the diagnosis of melanoma with Breslow's thickness more than 0.75 or 1.00 mm was investigated by receiver operating characteristic (ROC) analysis. Accuracy of classification was evaluated in terms of sensitivity, specificity, and area under ROC curves (AUC). RESULTS: The TDS assigned to cutaneous melanomas by the ABCD rule increased with the thickness of the lesions from in situ melanomas to melanomas of intermediate thickness (0.75-1.50 mm). As a preoperative method for the detection of melanomas with a Breslow thickness greater than 0. 75 mm, a TDS cut-off point of 6.80 showed 80% sensitivity, 84% specificity, and 82% diagnostic accuracy (AUC value, 0.90). TDS performed better in the diagnosis of a thickness threshold of 0.75 than 1.00 mm (higher AUC value). CONCLUSION: The TDS calculated by the ABCD rule of dermatoscopy-a simplified approach to dermatoscopic diagnosis of melanoma-provides useful information for the preoperative assessment of melanoma thickness greater than 0.75 mm.     

Comparison of dermatoscopic ABCD rule and risk stratification in the diagnosis of malignant melanoma

For didactic and documentation purposes the dermatoscopic ABCD rule and the dermatoscopic risk stratification have been proposed. The aim of this investigation was to compare the ability of the 2 methods to separate patients with cutaneous malignant melanoma from individuals with other pigmented skin lesions. Three dermatologists, experienced users of dermatoscopy, assessed macroscopic clinical and dermatoscopic slides from 258 patients referred to the skin cancer outpatient clinic by the ABCD rule and risk stratification methods. Diagnostic performance of the 2 methods was compared by receiver operating characteristics curve analysis. When all pigmented skin lesions were compared, there was a trend for the observers to perform better using risk stratification. When only lesions with a well-defined pigment network were included, the diagnostic performance of the risk stratification method was superior to the dermatoscopic ABCD rule (areas under the receiver operating characteristics curve median 0.93 vs. 0.80, p<0.004) for all observers. The agreement between the 2 methods was moderate to substantial (kappa coefficient 0.53-0.62). More melanomas were identified when the rules were combined. The dermatoscopic ABCD rule has been accepted as a standard for identifying melanomas with the dermatoscope, but should be considered secondary to pigment network analysis.     

Principles of dermatoscopy of pigmented skin lesions

There has been a dramatic increase in the incidence of malignant melanoma in most parts of the world. Because the tumor thickness is the most important prognostic factor for the prognosis of the malignant melanoma, the early detection of thin melanomas is essential. Dermatoscopy allows the physician to discriminate between melanocytic and nonmelanocytic lesions with high diagnostic accuracy and to detect initial malignant melanomas. We review the principles of dermatoscopy and the differential diagnosis of pigmented skin lesions. Before using the ABCD rule of dermatoscopy to classify melanocytic lesions into benign, suspicious, or malignant, the distinction between melanocytic and nonmelanocytic lesions is necessary. An essential prerequisite for the usefulness of this technique is adequate training.     

Application of an artificial neural network in epiluminescence microscopy pattern analysis of pigmented skin lesions: a pilot study

In vivo epiluminescence microscopy (ELM) is a non-invasive technique which improves the clinical diagnosis of naevi and malignant melanoma by providing diagnostic criteria that cannot be appreciated by the naked eye. The present study investigated whether ELM criteria pattern analysis can be employed in an objective, observer-trained, computer-aided diagnostic system, and whether artificial neural networks (ANN) can be applied to the diagnosis of pigmented skin lesions (PSL). The ELM criteria patterns of 200 PSL oil immersion images (60 common naevi, 60 dysplastic naevi, and 80 malignant melanomas) were analysed using a standardized questionnaire. One hundred randomly assigned PSL were used as a training set for an ANN, the remaining 100 PSL serving as the test set. The ANN was trained by backward propagation according to the histological diagnosis, and its performance was compared with that of human investigators. Out of the test set the human investigators correctly diagnosed 88% of PSL and the ANN 86%. in a dichotomized model comparing common, compound, and dysplastic naevi vs. malignant melanoma, i.e. benign vs. malignant PSL, the sensitivity and specificity of human diagnosis was 95 and 90%, respectively, whereas the sensitivity and specificity of the ANN diagnosis was 95 and 88%. Our data indicate that artificial neural networks can be trained to diagnose PSL at a human expert level, based on patterns provided by ELM criteria. We suggest that this technique offers a new approach to the diagnosis of PSL.     

Laypersons' perceptual discrimination of pigmented skin lesions

BACKGROUND: Most cutaneous malignant melanomas of the skin are visible and should, at least in theory, be possible to detect with the naked eye. OBJECTIVE: This study was conducted to learn more about laypersons' ability to discriminate between benign pigmented lesions and malignant ones. METHODS: Four groups of laypersons (n = 120) were asked to evaluate pictures of different types of pigmented skin lesions, before and after they received information about the ABCD (asymmetry, border irregularity, color variegation, and diameter greater than 6 mm) criteria, with respect to the necessity of action. RESULTS: The respondents made adequate assessments of melanomas but overestimated the danger of benign pigmented skin lesions. Information about the ABCD criteria enhanced their ability to make adequate assessments. CONCLUSION: People seem to make adequate decisions concerning how to act if they have a melanoma. On the other hand, common moles and dysplastic nevi were harder to discriminate. Providing information to the public about the features of melanomas, in accordance with the ABCD criteria, might help laypersons in their perceptual discrimination of skin lesions.     

Current technologies for the in vivo diagnosis of cutaneous melanomas

The rising incidence of cutaneous malignant melanoma has been observed in the past decades. Currently, there is no cure for metastatic melanoma; only early diagnosis followed by prompt excision of cutaneous lesions ensures a good prognosis. The clinical ABCD rule is created as a framework for differentiating melanomas from benign pigmented skin lesions, and it serves as the basis for current clinical diagnosis. The ABCD rule relies on four simple clinical morphologies of melanoma: 1) Asymmetry, 2) Border irregularity, 3) Color variegation, and 4) Diameter greater than 6 mm. Although it is valuable, it has its limitations. Currently, the diagnostic accuracy for physicians is about 65%. This statistic implies that 1) melanomas with subtle signs are missed as benign lesions, and 2) benign lesions are over diagnosed as melanomas, which lead to unnecessary biopsies.     

Korrelation auflichtmikroskopischer Charakteristika maligner Melanome mit den Tumor- Invasionsstufen nach Clark

Many epiluminescence microscopy (ELM) characteristics of malignant melanoma support the differential diagnosis of pigmented skin tumors. A preinvasive evaluation of level of invasion would be valuable for planning the excision margins. Since sonography for tumor thickness measurement is rarely available in a practice we searched for specific ELM criteria correlating with Clark's level of invasion. In our retrospective study of 120 malignant melanomas of 30 ELM features were studied for their correlation and the association was significant for 15 features.The following criteria were found only in level III-IV melanomas: intralesional horizontally elongated blood vessels, spontaneous microhemorrhages, plaster-of-Paris-like lacunae, grey-blue/yellowish-brown/reddish saccular pattern and eccentric nodes (reddish, livid, blue). 7 characteristics were predominantly found in level III-IV melanomas and seldom in "thin" melanomas (level I-II): deeply localized gray-blue/-brown fragmentary network, whitish-opaque septa, whitish- or bluish-opaque veil, negative pigmented network, areola with evenly arranged capillaries, polymorphic capillaries. Perivascular melanophages, eccentric dark blotches, pseudotrabeculae of melanophages and greyish-blue annular perifollicular pigmentations were the most significant association of ELM criteria in "thin" melanomas (level I-II). Epiluminescence microscopy is not only a tool for the differentiation of melanocytic lesions but also for a preinvasive evaluation of Clark's level of invasion.     

Cutaneous melanoma: uncommon presentations

Melanoma is the most important nonepithelial skin cancer. The diagnosis is usually made by clinical examination including dermatoscopy and histology. There are, however, variants of melanoma that miss the characteristic signs of pigmented lesions which are easily detectable when using the ABCD rule.     

Dermatoscopic pitfalls in differentiating pigmented Spitz naevi from cutaneous melanomas

Epiluminescence microscopy (ELM, skin surface microscopy, dermoscopy, dermatoscopy) is a valuable method for improving the diagnostic accuracy in pigmented skin lesions. Specific ELM criteria are already recognized for differentiating pigmented Spitz naevi (PSN) from cutaneous melanomas (CM). Our purpose was to describe the ELM appearance of a series of PSN with emphasis on PSN and CM with overlapping features. Thirty-six consecutive patients with PSN, and three cases of CM (selected from a larger database) exhibiting ELM 'spitzoid' features, were evaluated clinically, dermatoscopically and histopathologically. Most PSN (27 of 36; 75%) displayed two typical ELM patterns, namely, the starburst (19 of 36; 53%) or the globular pattern (eight of 36; 22%), which were correlated to different histopathological findings. In nine of 36 (25%) PSN, atypical ELM features which are more commonly seen in CM were observed. These PSN with an atypical pattern were characterized by an uneven distribution of colours and structures, and an irregular diffuse pigmentation resembling blue-white veil or irregular extensions (black blotches). These atypical lesions mostly occurred in children and showed no history of growth. In contrast, in three examples of CM, the typical ELM criteria of malignancy were less recognizable and either the characteristic starburst or globular pattern usually seen in PSN was present. These three lesions occurred in adults and had a recent history of change in colour, shape or size. The overlap in ELM features of some PSN and CM represents a major diagnostic pitfall when ELM examination is considered alone. In these atypical cases, clinical history including the age of the patient may be the only clue to enable a correct diagnosis.     

Surface microscopy of pigmented basal cell carcinoma

OBJECTIVES: To describe the relevant morphologic features and to create a simple diagnostic method for pigmented basal cell carcinoma (BCC) using in vivo cutaneous surface microscopy (ie, dermoscopy, dermatoscopy, or oil epiluminescence microscopy). DESIGN: Pigmented skin lesions were photographed in vivo using immersion oil (surface microscopy). All pigmented skin lesions were excised and reviewed for histological diagnosis. Photographs of 142 pigmented BCCs, 142 invasive melanomas, and 142 benign pigmented skin lesions were randomly divided into 2 equally sized training and test sets. Images from the training set were scored for 45 surface microscopy features. From this a model was derived and tested on the independent test set. SETTING: All patients were recruited from the primary case and referral centers of the Sydney Melanoma Unit, Sydney, Australia, and the Skin and Cancer Unit, Skin and Cancer Associates, Plantation, Fla. PATIENTS: A random sample (selected from a larger database) of patients whose lesions were excised. MAIN OUTCOME MEASURES: Sensitivity and specificity of the model for diagnosis of pigmented BCCs. RESULTS: The following model was created. For a pigmented BCC to be diagnosed it must not have the negative feature of a pigment network and must have 1 or more of the following 6 positive features: large gray-blue ovoid nests, multiple gray-blue globules, maple leaflike areas, spoke wheel areas, ulceration, and arborizing "treelike" telangiectasia. On an independent test set the model had a sensitivity of 97% for the diagnosis of pigmented BCCs and a specificity of 93% for the invasive melanoma set and 92% for the benign pigmented skin lesion set. CONCLUSION: A robust surface microscopy method is described that allows the diagnosis of pigmented BCCs from invasive melanomas and benign pigmented skin lesions. Arch Dermatol. 2000;136:1012-1016     

Comparison of dermatoscopic diagnostic algorithms based on calculation: The ABCD rule of dermatoscopy,the seven‐point checklist,the three‐point checklist and the CASH algorithm in dermatoscopic evaluation of melanocytic lesions

Dermatoscopic analysis of melanocytic lesions using the CASH algorithm has rarely been described in the literature. The purpose of this study was to compare the sensitivity, specificity, and diagnostic accuracy rates of the ABCD rule of dermatoscopy, the seven‐point checklist, the three‐point checklist, and the CASH algorithm in the diagnosis and dermatoscopic evaluation of melanocytic lesions on the hairy skin. One hundred and fifteen melanocytic lesions of 115 patients were examined retrospectively using dermatoscopic images and compared with the histopathologic diagnosis. Four dermatoscopic algorithms were carried out for all lesions. The ABCD rule of dermatoscopy showed sensitivity of 91.6%, specificity of 60.4%, and diagnostic accuracy of 66.9%. The seven‐point checklist showed sensitivity, specificity, and diagnostic accuracy of 87.5, 65.9, and 70.4%, respectively; the three‐point checklist 79.1, 62.6, 66%; and the CASH algorithm 91.6, 64.8, and 70.4%, respectively. To our knowledge, this is the first study that compares the sensitivity, specificity and diagnostic accuracy of the ABCD rule of dermatoscopy, the three‐point checklist, the seven‐point checklist, and the CASH algorithm for the diagnosis of melanocytic lesions on the hairy skin. In our study, the ABCD rule of dermatoscopy and the CASH algorithm showed the highest sensitivity for the diagnosis of melanoma.     

Modified ABC-point list of dermoscopy: A simplified and highly accurate dermoscopic algorithm for the diagnosis of cutaneous melanocytic lesions

BACKGROUND: The use of dermoscopy (epiluminescence microscopy, surface microscopy, dermatoscopy) improves clinical diagnostic sensitivity by 10% to 27%, particularly achieved by different algorithms or scores. OBJECTIVE: We sought to develop a simplified and highly accurate dermoscopic-point list for cutaneous melanocytic lesions. METHOD: We studied consecutive patients with suspicious melanocytic lesions, which were excised and histopathologically examined at our institution. On the basis of the ABCD rule of Stolz, Menzies score, and the modified ABCD rule of Kittler, a simplified ABC-point list was developed. Simple points were given for the following: asymmetry of outer shape (A) or differential structures inside the lesion in at least 1 axis ((A)); the abrupt cutoff of network at the border in at least one quarter of circumference (B); 3 or more colors (C); 3 or more differential structures (D); or noticed change (evolution) in the last 3 months (E). Using 20-fold magnification of computer dermoscopy, the sensitivity, specificity, and diagnostic accuracy were examined in 269 cutaneous melanocytic lesions. Of these, 84 (31.2%) were cutaneous melanomas. Also, the sensitivity, specificity, and diagnostic accuracy were investigated with a 7-point checklist and the 7 features for melanoma. RESULTS: With the ABC-point list for the diagnosis of cutaneous melanoma, sensitivity was 90.5%, specificity was 87%, and diagnostic accuracy was 88.1%, confirmed by cross-validation. The ABCD rule resulted in 90.5%, 72.4%, and 78.1%; Menzies score in 95.2%, 77.8%, and 83.3%; 7-point checklist in 90.5%, 87%, and 88.1%; and 7 features for melanoma in 94%, 74.6%, and 80.7%, respectively, CONCLUSIONS: The ABC-point list is simpler than the already established algorithms. Despite its simplicity, a high sensitivity, specificity, and diagnostic accuracy was achieved. This simplified approach in dermoscopic diagnostics may contribute to further spread and enable to learn and use this method more easily.     

Incidence of new and changed nevi and melanomas detected using baseline images and dermoscopy in patients at high risk for melanoma

OBJECTIVE: To determine the incidence of new, changed, and regressed nevi and melanomas in a cohort of patients at high risk for melanoma using baseline total body photography and dermatoscopy. DESIGN: Cohort study of patients at high risk for melanoma who underwent baseline cutaneous photography between January 1, 1992, and December 31, 1997, and had at least 1 follow-up visit by December 31, 1998. SETTING: Private practice rooms of 1 dermatologist in conjunction with a public hospital-based, multidisciplinary melanoma clinic in Victoria, Australia. PATIENTS: A total of 309 patients who had at least 1 of the following risk factors for melanoma: personal history, family history, 100 or more nevi, or 4 or more dysplastic nevi. MAIN OUTCOME MEASURES: Number of new, changed, and regressed nevi and melanomas detected and excised during the study interval. RESULTS: The incidence of new, changed, and regressed nevi decreased with increasing age (P<.001), whereas the incidence of melanomas increased (P = .05). The number of dysplastic nevi at baseline was positively associated with the incidence of changed nevi (P<.001) and melanomas (P = .03). The use of baseline photography and dermatoscopy was associated with low biopsy rates and early detection of melanomas. The development of melanoma in association with a preexisting nevus was not directly correlated with a change in a preexisting lesion monitored by baseline photography. CONCLUSIONS: Nevi are dynamic, and only a small percentage of all new and changed melanocytic lesions are melanomas. Patients younger than 50 years had a lower incidence of melanomas and a higher rate of new, changed, and regressed nevi when compared with patients older than 50 years. A new or changed pigmented lesion is more likely to be a melanoma in patients older than 50 years.     

Dermoscopy of pigmented lesions on mucocutaneous junction and mucous membrane

Background The dermoscopic features of pigmented lesions on the mucocutaneous junction and mucous membrane are different from those on hairy skin. Differentiation between benign lesions and malignant melanomas of these sites is often difficult. Objective To define the dermoscopic patterns of lesions on the mucocutaneous junction and mucous membrane, and assess the applicability of standard dermoscopic algorithms to these lesions. Patients and methods An unselected consecutive series of 40 lesions on the mucocutaneous junction and mucous membrane was studied. All the lesions were imaged using dermoscopy devices, analysed for dermoscopic patterns and scored with algorithms including the ABCD rule, Menzies method, 7‐point checklist, 3‐point checklist and the CASH algorithm. Results Benign pigmented lesions of the mucocutaneous junction and mucous membrane frequently presented a dotted‐globular pattern (25%), a homogeneous pattern (25%), a fish scale‐like pattern (18·8%) and a hyphal pattern (18·8%), while melanomas of these sites showed a multicomponent pattern (75%) and a homogeneous pattern (25%). The fish scale‐like pattern and hyphal pattern were considered to be variants of the ring‐like pattern. The sensitivities of the ABCD rule, Menzies method, 7‐point checklist, 3‐point checklist and CASH algorithm in diagnosing mucosal melanomas were 100%, 100%, 63%, 88% and 100%; and the specificities were 100%, 94%, 100%, 94% and 100%, respectively. Conclusion The ring‐like pattern and its variants (fish scale‐like pattern and hyphal pattern) are frequently observed as well as the dotted‐globular pattern and homogeneous pattern in mucosal melanotic macules. The algorithms for pigmented lesions on hairy skin also apply to those on the mucocutaneous junction and mucous membrane with high sensitivity and specificity.     

Dermoscopic study of cutaneous malignant melanoma: descriptive analysis of 45 cases

IntroductionDermoscopy or epiluminescence microscopy is a novel in vivo technique that can be used for the diagnosis of pigmented cutaneous lesions. The aim of this study was to analyze the dermoscopic patterns observed in a consecutive series of primary cutaneous melanomas.Material and methodsA cross-sectional study was carried out in which clinical, histological, and dermoscopic characteristics were analyzed in 45 primary melanomas.ResultsTwo thirds of the series were thin melanomas and 50 % were in situ melanomas. According to the ABCD rule, there was clinical suspicion of melanoma in 72 % of the lesions. Specific dermoscopic patterns were observed in 93 %. A multicomponent pattern was the most commonly observed (71 %). A nonspecific pattern was observed in 7% of lesions. The most noteworthy local findings were irregular pigmented patches (80 %), irregular dots and globules (68 % and 62 %), atypical pigmented network (57 %), blue-gray veil (42 %), and radial streaming and pseudopods (20 %). In addition, hypopigmented areas (86 %), regression structures (80 %), and vascular abnormalities (73 %) were also often seen. Acral lesions presented patterns characteristic of these sites.ConclusionAnalysis of dermoscopic patterns aids early definitive diagnosis of melanoma and is particularly useful in the case of clinically indolent lesions. Dermoscopic findings provide information complementary to that obtained by conventional histology.     

Dermatoscopy in the diagnosis of pigmented skin lesions: a new semiology for the dermatologist.

Dermatoscopy or epiluminescence microscopy (ELM), is a noninvasive method that enables clinicians to evaluate fully--by means of a magnified oil immersion diascopy--numerous morphological features, not visible with the naked eye, which enhance the diagnosis of nearly all pigmented skin lesions. In recent years, a burst of research activity in this topic has been carried out, dealing with different aspects, and new frontiers, of this technique. First, a continuous refinement of dermatoscopic terminology is undertaken, paying particular attention to the diagnostic performance of dermatoscopy at peculiar anatomical sites and to the building of different dermatoscopic algorithms aimed at a simplified diagnosis of melanoma, even for less experienced observers. Another point of interest concerns the possible role of dermatoscopy in the pre-operative assessment of melanoma thickness. Finally, promising data about the role of digital equipment in the follow up of melanocytic skin lesions as well as in the automated diagnosis of pigmented skin lesions have been recently reported. This paper should enable readers to become familiar with the procedure and terminology of ELM in the diagnosis of pigmented skin lesions encouraging a greater understanding of different methods (pattern analysis, algorithms) in the diagnosis of melanoma using ELM.     

Benign dermoscopic network patterns in dysplastic melanocytic nevi

Background/aims: Epiluminescence microscopy (ELM) is a non-invasive clinical technique, which by employing the optical phenomenon of oil immersion makes surface structures of the skin accessible for in vivo examination and provides additional criteria for the diagnosis of pigment skin lesions (PSLs). Many ELM criteria have been described. One of the most important ELM criteria is the pigment network (PN).
Objective: The aim of this study is to identify benign ELM (dermoscopic) network patterns of dysplastic melanocytic nevi (DMN).
Methods: This study included 907 dysplastic melanocytic nevi in 178 patients. Prior to biopsy, each lesion was photographed with oil immersion, and the images were viewed on a high-resolution compact slide projector. For each PSL, the ELM Network Features and ABCD-score were evaluated.
Results and discussion: The benign dermoscopic network features in DMN are the presents of a regular PN with delicate lines and margins, which predominantly thins out at the border of the lesion. For DMN, with these features, the mean ABCD score is smaller than ABCD-score for DMNs with irregular, prominent PN and network patches, ending abruptly at the periphery. In DMN with a network predominantly thinning out at the border of the lesion several uniform network patterns were found—diffuse network pattern, patchy network pattern, structureless center pattern, globular center pattern, and pigmented-blotch center pattern.
Conclusions: Benign features of pigment network are regularity, delicacy and thinning out at the border of the lesion. Benign dermoscopic network patterns are diffuse network pattern, patchy network pattern, structureless center pattern, globular center pattern, and pigmented-blotch center pattern. They can be found in DMN with a network predominantly thinning out at the border of the lesion.     

Dermatoscopy of "dysplastic nevi": a beacon in diagnostic darkness

The sequential progression model for melanocytic tumours from common nevus to malignant melanoma was proposed by Clark almost 30 years ago. The "dysplastic nevus" has frequently been considered a logical offspring of this concept and as a direct precursor of melanoma, analogous to the epithelial dysplasia-carcinoma sequence. Despite the use of modern molecular methods, there is no consensus as to if the dysplastic nevus represents a true precursor lesion of melanoma, a separate distinct type of nevus, or a diagnostic dilemma. Currently, the concept of melanocytic dysplasia remains subject to confusing definitions at all levels of the diagnostic process, i.e. clinical appearance, dermatohistopathology, and molecular biology. In this review, we collect evidence that nevi fulfilling Clark and Elder's classic histological criteria mostly represent "endpoints" of nevocytic evolution, whereas a minority of "dysplastic nevi" represent true melanoma precursors. The unsolved dilemma is that neither clinical, histopathological nor molecular criteria exist to make a distinction between dysplastic nevi and early melanomas. Our analysis of the current knowledge on dysplastic nevi shows that dermatoscopy remains the only quantifiable, easily applicable and reproducible diagnostic tool to approach the problem. Due to a "quantum leap" in optical resolution, objective scores can be established, e.g. the total dermatoscopy score (TDS) according to the ABCD rule, and documentation of changes over time are possible by digital image storage devices. Although dermatoscopy does not solve the dilemma of discriminating early, basically feature-less melanomas from dysplastic nevi, and it does not prove that dysplastic nevus is a distinct entity, it helps make melanocytic tumours with unclear malignant potential a manageable disease.     

Small diameter melanoma: a follow-up of the Norwegian Melanoma Project

BACKGROUND: Melanoma prognosis is dependent upon early recognition and treatment. There is a need for good clinical guidelines that focus on the early signs of melanoma. The ABCD (asymmetry, border, colour and diameter) rule states that most melanomas are more than 6 mm in diameter. Critics crave a modification, arguing that small diameter melanomas are not infrequent. OBJECTIVES: The aim of the present study was to describe the frequency and prognosis of melanomas less than 7 mm in a clinical setting. METHODS: The Norwegian Melanoma Project was conducted as a multicentre, prospective study with inclusion criteria. Patients were recruited from five dermatological departments in Norway from 1990 to 1993. RESULTS: The frequency of small melanomas was 11.4% (18/158). One-third was in situ melanoma, the rest invasive with a median thickness of 0.8 mm. Four small melanomas were T2 lesions, with a Breslow thickness of more than 1 mm. One nodular T2 melanoma recurred locally 2 years after diagnosis and the patient died of distant metastasis only months later. CONCLUSIONS: The ABCD rule remains a practical guide for early recognition of melanoma. Clinicians must be aware of its limitations.