Black carbon deposits outline all of air spaces and, around and below the hilum, there are areas of densely pigmented black fibrosis known as massive pulmonary fibrosis. The skin specimen on the right shows a tattoo of a snake under attack from an eagle. A tattoo is a form of localized, exogenous pigmentation of the skin. The pigments inoculated into the dermis are phagocytosed by dermal macrophages, in which they remain for the life. The pigments do not provoke any inflammatory response.
Common pigments used include cobalt blue, chrome green and mercuric salts for the reds.
The photomicrograph on the left shows normal skin stained with the Masson Fontana stain which demonstrates melanin granules. The majority of the basal keratinocytes contain finely dispersed melanin pigment. This has been transferred into the keratinocytes from the melanocytes where it was synthesized, via the melanocytic dendritic processes. The photomicrograph on the right shows a freckle stained with the Masson Fontana stain. There is a very intense pigmentation of the basal keratinocytes and melanocytes by melanin pigment.