Dermoscopy and reflectance confocal microscopy of balloon cell nevi: a series of 10 cases.

Background: Balloon cell nevus (BCN) is a rare histopathological entity. It is usually represented by an asymptomatic brown smooth or polypoid lesion, but no clinical features allow differentiation from other melanocytic nevi. Moreover, dermoscopy and reflectance confocal microscopy (RCM) aspects of BCN have been described in a few single cases. This study aims to describe a wider BCN series with dermoscopic and RCM features to assess the most frequent patterns.

Methods: Ten patients who underwent a BCN surgical excision with histological diagnosis were included in this study. Dermatoscopy and RCM were performed for each lesion, searching for the features described in literature.

Results: Each nevus presented as an asymptomatic, smooth brownish lesion. Regarding dermoscopy, four balloon cell nevi showed yellow globules, eight white globules, eight a light-brown network at the periphery, and eight a structureless central area; moreover, we found a hyperpigmented central blotch in four cases. RCM examination highlighted aggregates of dense nests at superficial dermis level in all BCNs, characterized by the presence of a dark nucleus surrounded by vacuolized cytoplasm. Moreover, multiple melanophages were seen at the dermal-epidermal junction in one case and superficial epidermal dendritic cells in one case.

Conclusions: This series of 10 BCNs improves the dermoscopic and confocal microscopic knowledge of this rare entity. We also reported a new dermoscopic aspect represented by central hyperpigmented blotch. A correct identification of BCN with noninvasive techniques allows to avoid unnecessary surgical excision.