Melanoma simulators: a retrospective study of nonmelanocytic mimickers.

Abstract

Cutaneous melanoma is an aggressive malignancy whose early detection is crucial for prognosis; however, some lesions can mimic nonmelanocytic conditions, leading to diagnostic errors. This retrospective study evaluated the frequency and characteristics of melanomas initially misclassified as nonmelanocytic lesions. All excised cutaneous lesions at the Dermatology Unit of the University Hospital Federico II of Naples between January 2021 and December 2024 were analyzed. Among 1500 histologically confirmed melanomas, 70 cases (4.7%) were initially diagnosed as nonmelanocytic based on clinical and dermoscopic evaluation. The most frequent misdiagnoses were basal cell carcinoma (40%), seborrheic keratosis (14.3%), and squamous cell carcinoma (8.6%). Other less common misclassifications included dermatofibroma, actinic keratosis, and vascular or adnexal lesions. The proportion and distribution of these cases remained stable over time, with no statistically significant differences across the study period. Amelanotic and hypomelanotic melanomas were particularly prone to misinterpretation due to the absence of typical pigmentation, often resembling inflammatory, vascular, or keratinizing lesions. These findings highlight the significant clinical heterogeneity of melanoma and the limitations of dermoscopy in atypical presentations. An integrated diagnostic approach combining clinical evaluation, dermoscopic assessment, patient risk factors, and a low threshold for histopathological examination remains essential. Increased awareness of melanoma simulators is crucial to reduce diagnostic delays and improve patient outcomes.