Clinical Application and Limitations of the Fluorescence In Situ Hybridization (FISH) Assay in the Diagnosis and Management of Melanocytic Lesions: A Report of 3 Cases

Histopathologic examination is the gold standard for the diagnosis of melanocytic lesions, including melanoma, and guides management options and disease prognosis based on the depth of invasion. Although most melanomas can be readily distinguished from benign nevi, some pigmented lesions are more ambiguous and can be challenging to interpret as truly benign or truly malignant. Unfortunately, misclassification can render severe consequences for the patient, making it imperative to explore further analysis to determine the true nature of an ambiguous lesion. A relatively new technique known as fluorescence in situ hybridization (FISH) has become prevalent in dermatopathology for distinguishing between benign and malignant pigmented lesions; however, there are few reports on the application of FISH results in the clinical setting. We present 3 cases in which a FISH assay was utilized to assist in the diagnosis and management of ambiguous pigmented lesions. We also provide a review of the most recent literature regarding this diagnostic modality.