At higher magnification, it often is difficult to discern abnormal melanocytes within the epidermis well above the basal layer, most of the fascicles being situated at the dermo-epidermal junction. As a rule, what melanocytes there are within the epidermis do not extend for any distance beyond the intradermal component of the neoplasm. In some instances, an increased number of melanocytes within the epidermis may be disposed as solitary units and arranged in nests that are not equidistant from one another and vary considerably in size and shape. A few melanocytes may be present above the dermo-epidermal junction, some of them even scattered in the upper reaches of the epidermis and far down the few remaining epithelial structures of adnexa. Melanocytes with plump oval, spindle, and polygonal shapes predominate, but "pagetoid" melanocytes with large roundish nuclei and abundant pale cytoplasm that houses "dusty" melanin are observed uncommonly. Fascicles of melanocytes at the dermo-epidermal junction tend to be oriented vertical to the skin surface. Cytologically, nuclei of melanocytes are large and pleomorphic, sometimes strikingly, and nucleoplasm is vesicular and heterochromatic. Nucleoli are prominent, sometimes red or purple, and often positioned in the center of the nucleus. Mitotic figures are invariable throughout the neoplasm, at times even being identified at the base of it. Some mitotic figures may be abnormal. Individual melanocytes may be necrotic as evidenced by pyknosis and/or karyorrhexis, and there may be foci of necrosis en masse. Long coarse dendrites of melanocytes may be noted, particularly in the dermis. Infiltrates of lymphocytes may be distributed in patchy fashion throughout the neoplasm, but are most dense at the periphery, and especially the base, of it. Satellite metastases may be observed in the same section of tissue that houses the primary melanoma; uncommonly, neoplastic melanocytes are identifiable in blood vascular and lymph vascular channels. Neurotropism may be detectable.

Metastases of melanoma in the same section of tissue as houses the primary melanoma may resemble the primary histopathologically, but often the cytopathological features are an exaggeration of it. The amount of melanin in a metastasis varies from scant to abundant.

In no instance was a diagnosis of melanoma made straightforwardly by the original histopathologist (Table 4). In three instances melanoma was mentioned as a possibility, but in each of those cases the first diagnosis given was "atypical Spitz's nevus." In two instances, the sole diagnosis was "atypical Spitz's nevus," in two "Spitz's nevus," and in two "cellular blue nevus."