Pilot study on the correlation between dermoscopic patterns and fluorescence in situ hybridization findings using whole-slide digital imaging for acral volar melanocytic lesions.

Dermoscopic evaluation of acral volar skin is helpful in differentiating malignant melanomas (MM) from benign melanocytic nevi. However, histological diagnosis remains difficult because sufficient evidence of histopathological changes to establish a diagnosis of MM are not easily obtained. The aim of the present study was to evaluate the effective use of fluorescence in situ hybridization (FISH) in the diagnosis of acral volar melanocytic lesions, and to determine whether acral volar melanocytic lesions show characteristic molecular biological features of malignant melanoma via FISH. We classified acral volar melanocytic lesions showing junctional findings into three groups: (A) parallel ridge pattern (PRP) on dermoscopic examination with melanoma in situ; (B) PRP with insufficient melanocyte proliferation and atypia to diagnose malignant melanoma using hematoxylin-eosin staining; and (C) junctional nevi. We performed FISH analysis using the same tissue section that was used for hematoxylin-eosin staining. FISH positivity was seen in 80% (4/5) of the group A sections, and in 80% (4/5) of the group B sections. One case in group C was only 0.3% over the established criteria line (63.3% > 63% in RREB1). Our results suggest that FISH using whole-slide digital imaging may be useful in the diagnosis of early in situ MM when a typical PRP is observed in an acral volar skin lesion with non-diagnostic histopathology.