Dots/globules are sharply circumscribed, usually round or oval, variously sized black, brown or gray structures. Basically, dots/globules may be subdivided due to their shape and distribution into regular and irregular ones. Irregular dots/globules are black, brown or gray, round to oval, variously sized and shaped structures unevenly distributed throughout a lesion.
Dots/globules correlate to aggregations of pigmented melanocytes, melanophages or even clumps of melanin within the cornified layer, the epidermis, the dermo-epidermal junction, or the papillary dermis. The size and shape of dots/globules reflect the extent and form of the accumulation of these pigmented structures, whereas their color depends on the level of these pigmented aggregates within the epidermis and the superficial dermis. Pigmented structures are black in the cornified layer, brown at the dermo-epidermal junction and gray-blue in the papillary dermis. So, stereotypical black dots correlate to focal collections of melanocytes and clumps of melanin within the stratum corneum. In contrast, classic brown globules correspond to either discrete junctional nests of more or less heavily pigmented melanocytes or to a cap-like pigmentation of melanocytes (nevus cells) in the papillary dermis immediately beneath the epidermis.
Dots/globules may occur in benign and malignant melanocytic proliferations. In melanocytic nevi regular dots/globules may be observed in the center but also throughout the lesion. They are regular in size and shape, and are quite evenly distributed. In melanomas, irregular dots/globules, however, occur predominantly at the periphery and vary in size and shape, and, moreover, are unevenly distributed.
Red globules refer to round to oval, quite well circumscribed globules with a milky red coloration, commonly arranged into small clusters.
Histopatologically, red globules correspond to nests of non-pigmented melanocytes in the dermis. However, no meticulous clinico-pathologic correlation has yet been performed, at least to the best of our knowledge.
Red globules represent a newly described criterion, where the corresponding histopathologic structures are not yet fully elaborated. In our estimation, red globules are a helpful, albeit subtle finding that is occasionally but specifically seen in melanoma.