- Presence of atypical Melan-A-positive melanocytes surrounding dermal papillae and bulging into dermis (in situ melanoma)- Atypical melanocytes arranged in nests and presence of lymphocytes within dermal papillae (in situ melanoma)- Heavily pigmented keratinocytes of the basal layer of the epidermis combined with an increased number of junctional melanocytes (lentigo maligna). The gene discussed is MLANA; the disease is in situ carcinoma.