Plewig G
Hautarzt. 1976 Jul;27(7):340-3.
The clinical and histopathological picture of the pigmented epidermal cyst and the pigmented trichilemmcyst is illustrated by three case-reports. The pigment is melanin, which is located in the epithelium of the cyst-wall, the corneocytes of the lumen and in macrophages in the dermis. The clinical appearance of melanin pigmented cysts is blue due to the Tyndall-phenomenon.