Abstract
Early diagnosis when melanoma is still small and thin is essential for improving mortality and morbidity. However, the diagnosis of small size melanoma might be particularly difficult, not only clinically but also dermoscopically. This study aimed to define clinical and dermatoscopic parameters in the diagnosis of suspicious pigmented cutaneous lesions with a diameter of ≤ 6mm and determine the sensitivity, specificity, positive and negative predictive values as well as the accuracy of each clinical and dermatoscopic criterion. This is a transversal, descriptive and analytical study of dermatoscopic analysis with the gold standard being the pathologic examination obtained from the excisional biopsy of suspicious melanocytic lesions with a diameter of ≤ 6mm. Trunk and limb lesion data from a public health service and a private clinic were prospectively collected from 2011 to 2017 by a unique observer. In total, 481 melanocytic lesions were included, with 73.8% being ≤ 4mm in diameter. Overall, 123 were diagnosed as melanoma, 56.0% in situ and 22.0% as thin melanomas (Breslow index 0.1 to 1.0mm). Melanoma presented symmetry in 53.7% of cases, regular borders in 54.5% and a single color in 60.2%. Regarding evolution, 13.8% of melanomas versus 10.9% of benign lesions (p = 0.116) were new by comparing photos from baseline with photos from the follow-up. The majority of melanomas (65%) were found on the limbs compared to 37.2% of the benign lesions at this location (p<0.001). A multiple logistic regression model adjusted for age, gender and location was created. The independent variables associated with the diagnosis of melanoma ≤ 6mm, adjusted for age, gender and location, were: streaks (adjusted Odds Ratio [aOR] 2.5; 95% CI 1.3–4.7; p = 0.006), and the presence of a structureless area (aOR 2.2, 95% CI 1.2–4.0, p = 0.011). Conversely, a symmetric typical pigment network was a protection variable (aOR 0.4, 95% 0.7–0.9, p = 0.040). In conclusion, dermatoscopic criteria have been identified which help to diagnose cases of small size melanoma. These include streaks and structureless areas that can be taken, particularly in consideration for the diagnosis of this subset of small difficult melanomas.
Highlights
Cutaneous melanoma (CM) is the cancer with the highest mortality, despite representing only 1% of all skin cancers [1]
The analysis included 481 lesions with diameters not exceeding 6mm and which were suspected of cutaneous melanomas, resulting in the detection of 123 CMs (Table 1)
The accuracy of the clinical hypothesis (59.7%) and that of the dermatoscopic hypothesis (32%), separately, increased to 66.1%, when both hypotheses were associated. These results are in accordance with Grichnik [5], who suggests that dermoscopy should be considered as auxiliary to the clinical examination, but there are cases where dermoscopy alone is insufficient for a diagnosis of precocious melanomas, with the diagnostic accuracy increased by accessing the lesion dermoscopy in issue and comparing it with the remaining patient’s nevi (“ugly duck” sign)
Summary
Cutaneous melanoma (CM) is the cancer with the highest mortality, despite representing only 1% of all skin cancers [1]. To assist in the early diagnosis, dermatologists currently rely on dermoscopy At present, this is the most important tool to assess pigmented cutaneous lesions and allow the early excision and treatment of the CM in order to avoid the unnecessary removal of benign lesions. With the advent of the dermatoscope and routine examination of pigmented lesions, the number of melanomas in initial stages with sizes under the classic 6mm in diameter criterion by ABCD for CM are increasingly being detected [3,4,5,6,7,8,9,10,11,12,13,14,15,16]. This new dimensional frontier for melanomas has been reported in the literature in case reports as well as in case series, predominantly comparing them with larger melanomas, with many articles using the histopathological dimensions of the lesions [17,18,19,20,21,22,23,24]
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