Dark homogeneous streak dermoscopic pattern correlating with specific KIT mutations in melanoma

Usefulness of dermoscopy to improve the clinical and histopathologic diagnosis of skin cancers

Multiple studies have shown that dermoscopy increases the sensitivity and specificity for the detection of skin cancers compared with examination by the naked eye. Dermoscopy can also lead to the detection of thinner and smaller cancers. In addition, dermoscopy leads to the more precise selection of lesions requiring excision. In essence, dermoscopy helps clinicians differentiate benign from malignant lesions through the presence or absence of specific dermoscopic structures. Therefore, because most dermoscopic structures have direct histopathologic correlates, dermoscopy can allow the prediction of certain histologic findings present in skin cancers, thus helping select management and treatment options for select types of skin cancers. Visualizing dermoscopic structures in the ex vivo specimens can also be beneficial. It can improve the histologic diagnostic accuracy by targeted step-sectioning in areas of concern, which can be marked by the clinician before sending the specimen to the pathologist, or by the pathologist on the excised specimen in the laboratory. In addition, ex vivo dermoscopy can also be used to select tumor areas with genetic importance because some dermoscopic structures have been related to mutations with theragnostic relevance. In the second article in this continuing medical education series, we review the impact of dermoscopy on the diagnostic accuracy of skin cancer, how dermoscopy can affect the histopathologic examination, and which dermoscopic features may be more relevant in terms of histologic and genetic prediction.

Dermoscopic features predicting the presence of mitoses in thin melanoma

BACKGROUND

The latest AJCC classification has included the number of mitoses as a factor for upstaging thin melanomas. Meanwhile, while dermoscopy has often been used to predict melanoma thickness, its value in predicting number of mitoses remains unknown.

OBJECTIVE

Our aim is to evaluate the correlation between dermoscopic features and the presence of mitoses in a consecutive cohort of thin melanomas.

METHODS

A case control study has been performed to identify specific dermoscopic parameters that could differentiate thin melanomas with 1 or more mitoses per mm2 from those without mitoses.

RESULTS

Of 177 melanomas equal to or thinner than 1mm, 131 (74%) lesions had no mitoses and 46 (36%) lesions had at least 1 mitosis×mm2. Dermoscopic features associated with the presence of 1 or more mitoses were the following: peripheral streaks (OR 4.11; 95% CI 1.94-8.71) and black colour (OR 4.70; 95% CI; 2.28-9.68). In contrast, atypical pigment network (OR (0.30; 95% CI 0.15-0.61)) and brown colour (OR 0.36; 95% CI 0.18-0.75) were associated to melanomas without mitoses. The same variables were also associated to the increasing number of mitoses at linear regression.

CONCLUSION

Black colour and peripheral streaks can predict the presence of mitoses in thin melanoma, while atypical pigment network and brown colour are associated to thin melanoma without mitoses.

Conceptual approach to early melanoma detection: models, tools, issues and challenges

Identification and removal of melanoma early in its development remains the most effective treatment. However, identification of early melanoma remains challenging and may result in unnecessary morbidity due to the excess excision of benign melanocytic nevi. Herein, we present a conceptual model of benign and malignant melanocytic growths. The potential differences in the location of the cell of origin as well as considerations for neoplasm progression are also reviewed. Several of the clinical tools currently available, the integration of information from those different sources, and approaches to set an optimum biopsy threshold are discussed. While early detection remains a challenge, significant progress has been made. Insight into melanoma growth processes and appropriate use of available tools can result in the detection of thinner melanomas while also decreasing overall biopsy rates.

Dermoscopy: not just for dermatologists

Use of dermoscopy has been proven to increase diagnostic accuracy for melanoma. It is frequently used by dermatologists and other healthcare providers during skin cancer screening and in the evaluation of concerning skin lesions. Studies have shown that it is useful in the diagnosis of many nononcologic cutaneous diseases as well as in the monitoring of disease progression and treatment response. Furthermore, dermoscopy has the potential to aid in pathology specimen sectioning, translational research and medical technology development. Its broad applications and ease of use will make it an increasingly influential tool in healthcare. In this article, we review the established uses of dermoscopy by different healthcare providers and its potential future applications.

Melanocytic naevi with globular and reticular dermoscopic patterns display distinct BRAF V600E expression profiles and histopathological patterns

BACKGROUND

BRAF (v-raf murine sarcoma viral oncogene homologue B) V600E mutations have been detected with high frequency in melanocytic naevi. Few studies have stratified analyses by naevus dermoscopic pattern.

OBJECTIVES

To determine the frequency of BRAF V600E expression and histopathological pattern in acquired melanocytic naevi distinguished by a globular vs. reticular dermoscopic pattern.

METHODS

We retrospectively identified histologically proven melanocytic naevi with banal reticular or globular dermoscopic patterns and evaluated BRAF V600E expression using immunohistochemistry.

RESULTS

BRAF V600E expression was detected in 11 of 12 globular naevi vs. four of 13 reticular naevi (91·7% vs. 30·1%, P = 0·004). A predominantly dermal growth pattern (P < 0·001) and the presence of large junctional nests (P = 0·017) were each associated with a globular dermoscopic pattern. The presence of either a predominantly dermal growth pattern or large junctional nests was found in 13 of 15 naevi positive for BRAF V600E and in two of 10 naevi negative for BRAF V600E (86·7% vs. 20%, P = 0·002).

CONCLUSIONS

The frequency of BRAF V600E mutations differs in naevi distinguished by unique dermoscopic structures and microanatomical growth patterns. Globular naevi, which most often histologically correspond to a predominantly dermal growth pattern and/or the presence of large junctional nests, are significantly more likely to express BRAF V600E than reticular naevi. These preliminary results require validation, but may directly inform future studies of naevogenesis and melanoma genesis.