Structural correlations between dermoscopic features of cutaneous melanomas and histopathology using transverse sections

Interpretation of dermoscopic features of cutaneous melanoma is based on histologic description of perpendicular sections of the lesions that does not reflect the overview achieved by epiluminescence. We describe the utilization of transverse sections as a tool to define the histopathology of features that are the dermoscopic hallmarks of cutaneous melanoma. From a collection of 23 pigmented lesions with the dermoscopic diagnosis of cutaneous melanoma submitted for surgical excision we selected, from each specimen, one dermoscopic feature (black dots and globules, brown dots, blues dots and globules, depigmentation, broadened network, radial streams or pseudopods) that was sampled with a 4-mm punch (specimen) to obtain perpendicular and transverse sections. Using this strategy, it was possible to correlate the histopathology of all features that are often used as criteria for diagnostic dermoscopy. The black dots were pigmented neoplastic cells at the dermal-epidermal junction (DEJ) and within the epidermis in heavily pigmented columns. Similar findings were seen in brown dots, however there was slightly less pigment. No statistical difference was observed between brown dots and black dots regarding size, area and number of atypical cellnests. Blue dots correlated to melanophages, surrounding the superficial vascular plexus. Depigmentation was characterized by intense fibrosis of the papillary dermis. The pigmented network showed atypical pigmented or non-pigmented melanocytes at the DEJ and epidermis as well as heavily pigmented keratinocytes in the basal cell layer. The radial streaming and pseudopods had neoplastic cells in nests, a stratified growth pattern arranged in centrifugal linear extensions, resembling a arborescent branching. The results represented herein, are an important tool for understanding histopathological alterations responsible for dermoscopic features and for improving the efficacy of this diagnostic method.