Abstract

A-16-year old girl developed a red nodule on her left thigh. The lesion had already been shaven by a surgeon and been diagnosed histopathologically an amelanotic melanoma when she first visited our hospital. She says the nodule was about 5mm in diameter, dome shaped, red color and rough surface. Histopathplpgically, main lesion is almost symmetrical and excists in inverted triangle shape. The tumor cells are arranged mostly in fairly well circumscribed nests and the nests exist in the epidermal-dermal junction through the lower dermis. There also are nests in middle epidermis, but it is not remarkable. The tumor cells are almost epitheloid and have large nuclei. Maturation of cells are recognized with increasing depth. Mitosis is rare. Cellular DNA content is 2.82C whitch is higher than that of Spitz nevus reported before and tetraploid cells are more than usual. Although analysis of cellular DNA content sugested that it was malignant, histopathology showed Spits nevus.