Abstract

Background: A dysplastic nevus was classically described as a distinct lesion in melanoma-prone families that conferred increased risk of malignant transformation. Dysplastic nevi are sometimes difficult to differentiate from melanoma clinically, as they both can exhibit the ‘ABCDE’ features. Dermoscopy plays an important role by showing features of benign vs malignant pigmented lesions. In most cases, dysplastic nevi can easily be distinguished from melanoma histologically, however the degree of cytological atypia can be subjective. Reflectance confocal microscopy (RCM) is a noninvasive tool that can provide additional information in equivocal cases. Case presentation: Here, we discuss the case of a 37-year-old female who presented with an 8 mm brown papule on the left breast. Dermoscopy revealed atypical pigmentation with multiple colors suspicious for melanoma. RCM showed an irregular lesion with a central, well-organized nevus and patchy peripheral hyperpigmentation with atypical cells in the epidermis. There were numerous round atypical cells at the DEJs and a thickened, broadened, mesh-like pattern with many small and bright cells in the dermis. RCM findings suggested melanoma in situ, prompting a biopsy that showed a melanocytic nevus with severe atypia. However, given concern for melanoma both clinically and on RCM, the entire specimen was bread-loafed to produce 60 additional cross-sections. Second process revealed more marked, severe features and a focal area of regression in the dermis consistent with melanoma in situ. Conclusion: In cases where histological evaluation does not match with clinical impression, it is advisable to discuss the results with the pathologist, and if feasible, consider bread-loafing the specimen. In our case, the lesion was highly suspicious for melanoma clinically, dermoscopically and on RCM, but the initial slide showed a dysplastic nevus with severe atypia. Further processing revealed features consistent with melanoma in situ.

Financial Disclosure:
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