In vivo reflectance confocal microscopy imaging of vitiligo, nevus depigmentosus and nevus anemicus

Background/purpose: Hypopigmentary skin disorders such as vitiligo, nevus depigmentosus and nevus anemicus are common diseases in clinic. The lesions of these diseases could be similar to some extent, although each of them has its own characteristic clinical appearance and histological features. Clinically, the atypical lesions are often difficult to be differentiated. In vivo reflectance confocal microscopy (RCM) is a non-invasive, repetitive imaging tool that provides real-time images at a nearly cellular histological resolution. Our aim was to investigate the RCM features of vitiligo, nevus depigmentosus and nevus anemicus.

Subjects and methods: A total of 135 patients with a clinical diagnosis of the aforementioned diseases were included in this study. The RCM images from depigmented skin, border of the white macules, adjacent normal-appearing skin and distant normal skin for all patients at the dermo-epidermal junction (DEJ) level were investigated.

Results: In the active phase of vitiligo (AVP), the RCM demonstrated a complete loss of melanin in lesional skin in eight (53; 15.1%) patients. In 45 patients (53; 84.9%) of the AVP, part of the bright dermal papillary rings normally seen at the DEJ level disappeared or part of the rings lost their integrity and the content of melanin decreased obviously. In 20 patients (53; 37.7%) of the AVP, highly refractile inflammatory cells could be seen within the papillary dermis in the lesional and adjacent normal-appearing skin, which may indicate the lesion progresses. In addition, part of the dermal papillary rings showed lack of integrity or their brightness decreased in adjacent normal-appearing skin in all the patients of the AVP. It is important to know that the RCM demonstrated an ill-defined border. In the stable phase of vitiligo (SPV), the RCM demonstrates a complete loss of melanin in lesional skin and a clear border in 31 (41; 75.6%) patients; the content of melanin and dermal papillary rings in adjacent normal-appearing skin show no changes. In 10 (41; 24.4%) patients, the dendritic and highly refractile melanocytes arose in the recovery phase of vitiligo, which may indicate the repigmentation of vitiligo. There are three kinds of repigmentation patterns under RCM: marginal, perifollicular and diffuse. Distant normal skin showed no difference from controls in both the active and the SPV. In all the patients with nevus depigmentosus, the content of melanin decreases obviously but the dermal papillary rings are intact. The dermal papillary rings show no differences between lesional skin and adjacent normal-appearing skin of nevus anemicus.

Conclusion: Considering our results, RCM may be useful to non-invasively discriminate vitiligo, nevus depigmentosus and nevus anemicus in vivo.