A 36-year-old woman presented a pigmented lesion measuring 0.45cm in diameter on her left buttock (Fig. 1). The lesion had a homogeneous globular pattern in which the globules were small and regular but in a nonuniform distribution. After 4 months, the lesion showed asymmetric growth (Fig. 2). Examination by reflectance confocal microscopy revealed round pagetoid cells in the epidermis and dense nests and noncohesive nests with atypical cells in the dermis. The histopathological diagnosis was melanoma with a Breslow thickness of 0.57mm.

Figure 1

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Figure 2

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It has been observed that melanomas with different speeds of growth have distinct dermoscopic structures. Slow-growing melanomas usually have a reticular or homogeneous-reticular pattern, while the globular pattern has been associated with faster-growing melanomas.

Large, dark globules of different shape, size, or color or with an irregular distribution in the lesion are associated with melanoma.

The site on the buttock (where it is rare to find nevi with a globular pattern), the presence of irregularly distributed globules, the change observed during short-term follow-up, and the finding of atypical cells on confocal microscopy were key to the diagnosis of melanoma. Melanocytic lesions with an atypical globular pattern must be followed up early and, if changes are observed, surgical excision should be performed.