Clinical and histopathological studies on spotted grouped pigmented nevi with special reference to eccrine-centered nevus.

Clinical and histopathological studies on 16 cases of spotted grouped pigmented nevus resulted in this disease being classified into at least three types. Characteristic findings of each type are described in this paper, in particular that nevus cell proliferation, a finding common to each type, is closely related pathogenetically to skin appendages, especially with eccrine sweat ducts. The eccrine-centered nevus characterized by Mishima corresponds to the third type, according to the present author's classification. The similar characteristic histopathological finding was also observed in a specimen taken from a black papule in a case of giant pigmented nevus with disseminated pigment cell nevi. We would like to consider that the cells of eccrine-centered nevus are derived from nevoblasts present in the walls of sweat ducts.