Fluorescence <i>in situ</i> hybridization in melanoma diagnosis: Pros and cons

Melanocytic lesions frequently present diagnostic challenges due to their high degree of morphological heterogeneity. While histopathological examination remains the gold standard for melanoma diagnosis, alternative methods, such as fluorescence <i>in situ</i> hybridization (FISH), are used to support diagnosis in uncertain cases. FISH is a complementary diagnostic tool that can help differentiate between nevi and melanoma by detecting chromosomal anomalies. However, its accuracy is limited by false-positive and false-negative results. The present study assessed the utility and limitations of FISH in melanoma diagnosis by analyzing chromosomal anomalies in 18 melanocytic lesions previously classified as atypical nevi or melanoma based on dermoscopic and histopathological criteria. The results revealed that FISH confirmed nearly all atypical nevi as benign lesions (with the exception of one lesion); however, it failed to definitively confirm all melanomas. These findings highlight both the strengths and weaknesses of FISH, suggesting that while it is a useful adjunctive tool, it should not replace conventional histopathological examination. Instead, FISH should be interpreted with caution due to its potential for false-positive and false-negative results, underscoring the need for further studies to refine its diagnostic reliability.