[Malignant lentigo on glans penis. Differentiation using a new method].

A lentigo maligna melanoma on the glans penis and the orificium urethrae is described. From the clinical point of view a superficial spreading melanoma as well as a lentigo maligna could be considered as differential diagnoses. The flat part of this lesion, however, was a lentigo maligna when investigated using a lightmicroscope and especially fluorescence-microscope. In the lightmicroscope only single heavily pigmented and dendritically branched cells could be seen in the basal parts of the epidermis. The definite shape of the other tumor cells was not identifiable. With the fluorescence microscope, however, in nearly all fluorescing and atypical pigment cells, dendritic branching clearly was present.