Blue nevus of the prostate: ultrastructural study.

A case of blue nevus of the prostate in a sixty-five-year-old black patient was studied by light and electron microscopy. In the melanocytes only fully melanized melanosomes were present; melanosomes in early stages of development were entirely absent. It was concluded that the formation of melanosomes within the melanocytes in blue nevus of the prostate is probably under genetic control.