Correlation between the histopathology and the epiluminescence microscopy features of malignant blue nevus.

Background: The validation of epiluminescence microscopy (ELM) for the diagnosis of pigmented skin lesions is conditional on the demonstration of consistent histologic correlates of the ELM patterns. The ELM characteristics of malignant blue nevus (MBN) have never been reported previously.

Objective: To evaluate the histologic counterparts of the ELM features of a case of MBN.

Methods: Comparison between the histologic characteristics observed in step-sections of the lesion and the structures observed in a digital ELM image.

Results: On ELM, the lesion showed a diffuse whitish-blue veil, round black blotches, a collection of dark colored punctate spots, and fragmented bluish reticular-like formations in the periphery. At histologic examination, the black blotches and the spots appeared to correlate with areas of intense focal necrosis in the papillary and reticular dermis, and the reticular-like structures were demonstrated to correspond to the presence of free melanin and melanophages in the papillary dermis.

Conclusion: In this case of MBN, blotches and spots seen on ELM correlated with intense necrosis in the papillary and reticular dermis, and reticular-like formations were the counterparts of free melanin and melanophages in the papillary dermis.