Despite many findings in common with melanoma in postpubescents, there are major differences in architectural pattern and even in cytopathologic features between melanoma in prepubescents and postpubescents (Table 3). At scanning magnification, the most striking feature of melanoma in prepubescents is vertical orientation of a melanocytic neoplasm that fills much of the dermis and sometimes extends well into the subcutaneous fat. The lesion usually is only slightly asymmetrical with more melanocytes situated on one side of it than the other. Melanin is distributed very unevenly, sometimes being more abundant at the base of the neoplasm. Nests and fascicles of melanocytes within the dermis and the subcutaneous fat vary markedly in size and shape, and have become confluent to form a sheet of neoplastic cells in company with little, if any, discernible intervening background connective tissue. Some aggregations assume bizarre geometric shapes and some fascicles tend to be very elongated. Epithelial structures of adnexa are decreased markedly in number or absent altogether. At or near the surface, the cornified layer sometimes is compactly orthokeratotic, the viable epidermis thickened, and the upper part of the dermis distinctly edematous and punctuated by telangiectases.