Melanoma and naevi with a globular pattern: confocal microscopy as an aid for diagnostic differentiation.

Abstract

Dermoscopically, one of the most common findings in melanocytic lesions is a globular pattern. A regular globular pattern is a common finding in naevi. Melanoma can also show a globular pattern, with globules typically irregular in size, colour and distribution. To investigate the likelihood of diagnosing melanoma according to distinct dermoscopic and confocal aspects. Dermoscopic and confocal aspects of 83 excised melanocytic lesions dermoscopically showing globules were analysed. Our study population included 39 acquired melanocytic naevi, 16 Spitz naevi and 28 melanomas. Univariate analysis showed that regular distribution of globules on dermoscopy is associated with a ninefold lower risk for melanoma, whereas an irregular distribution is associated with an almost 10-fold increased risk for melanoma. Concerning confocal features, dense nests are associated with a fivefold lower risk for melanoma, whereas loosely arranged nests are associated with an almost sixfold risk for melanoma; moreover, the presence of round cells is associated with a 17-fold lower risk for melanoma, whereas pleomorphic cells are associated with an almost 16-fold risk for melanoma. So that melanoma is not missed, clinicians should carefully analyse globular lesions in adults, focusing, in particular, on the distribution of globules and on the presence of confocal cytological atypia.