Melanocytic clefting is associated with melanoma on LC-OCT

Line-field confocal optical coherence tomography (LC-OCT) provides in vivo images with cellular resolution for melanocytic lesions. To date, no descriptions have associated cellular discohesion forming clefts ('clefting') with malignancy in melanocytic lesions using in vivo imaging techniques such as reflectance confocal microscopy (RCM) or LC-OCT.

This study aimed to describe the feature of 'clefting' in melanocytic lesions and its correlation with histopathology and RCM.

Consecutive benign, atypical and malignant melanocytic lesions were scanned with LC-OCT at the Hospital Clinic of Barcelona, Hôpital Erasme and University Hospital of Saint-Etienne. Images of body and facial lesions were reviewed according to study criteria. Only lesions with a univocal or unambiguous diagnosis (clinically or histologically) were selected.

Clefting was found in 36 of the 200 analysed lesions. It was present in 28 of the 70 melanomas (40%) and in eight of the 130 benign lesions (6%). The odds ratio for malignancy associated with the presence of clefting in a melanocytic lesion was 10.03 (CI 4.07-27.5; p < 0.001). The magnitude of clefting also showed significant differences: marked clefting was present in 17 of the 70 melanomas (24%) and in only two benign lesions (2%), with an OR of 20.22 (CI 4.55-186.2; p < 0.001). No differences were observed regarding the presence of this feature in different locations. It was strongly associated with other malignant features, such as epidermal consumption, nests in the epidermis and disruption of the dermo-epidermal junction.

This study highlights that clefting observed in melanocytic lesions is not an artefact created by sample preparation, but a specific feature related to malignancy. Moreover, marked clefting is apparently associated with deeper melanoma invasion.