Melanocytic lesions with peripheral globules: results of an observational prospective study in 154 high-risk melanoma patients under digital dermoscopy follow-up evaluated with reflectance confocal microscopy

Abstract

Background: The management of melanocytic lesions with peripheral globules (MLPGs) is usually age-dependent and can be challenging in high-risk melanoma patients.

Objectives: To evaluate clinical, dermoscopic and reflectance confocal microscopy (RCM) features of MLPG in patients under digital dermoscopic surveillance. To know whether dermoscopic or RCM findings correlate with histologic diagnosis and the accuracy of the dermoscopy-RCM compared with histopathology.

Methods: During 24 months, we prospectively enrolled MLPG in patients under digital dermoscopy follow-up. All were evaluated by dermoscopy and RCM and excised for histologic examination.

Results: We enrolled 154 patients, mean age 42.45 years (18.78-73.19). Three melanomas and 19 dysplastic naevi (DNs) were diagnosed. There were no significant differences in the age of the patients (P = 0.662). MLPGs with diameter of 6 mm or more and asymmetry in two axes were associated with melanoma (P = 0.01, P = 0.003). Patients with more than one MLPG were less likely to have melanoma. Blue-grey and red colours were more frequent in melanoma (P = 0.013 and P = 0.000). Different sizes and shapes of PG were associated with DN and melanoma (P = 0.000 and P = 0.001). In a new lesion, PG in <25% of the circumference was related to malignancy (P = 0.010). RCM signs of malignancy were related to melanoma: pagetoid cells (P = 0.000), non-edged papillae (P = 0.001), atypical junctional thickenings (P = 0.000) and atypical cells at the dermal-epidermal junction (P = 0.000). Dense irregular nests were associated to melanoma (P = 0.019). Dermoscopy and confocal evaluation were able to diagnose 100% of melanomas and 84.21% of DNs. The kappa coefficient between dermoscopy-RCM vs. histology was 0.76.

Conclusions: We recommend to excise a MLPG when it presents asymmetry in two axes, 6 or more mm, new lesion with PG in less than the 25% of the circumference, irregular size and shape PGs and irregular dense nests on RCM, regardless of the patient's age.