Guidelines for histopathologic diagnosis of plantar malignant melanoma. Two-dimensional coordination of maximum diameters of lesions and degrees of intraepidermal proliferation of melanocytes

Detection of early lesions of malignant melanoma is highly important for the improvement of the prognosis. However, diagnosis of early malignant melanoma is not easy and is often discordant even among expert dermatopathologists. In this study, we propose guidelines for the histopathologic diagnosis of plantar malignant melanoma and malignant melanoma in situ on the sole. They are formulated with two-dimensional coordination of maximum diameters of the lesions and degrees of intraepidermal proliferation of solitary-arranged melanocytes. The guidelines are simple and reproducible, and surely contribute to the accurate diagnosis of early plantar malignant melanoma.