Forensic Dermatology of Postmortem Tanning: A Unique Phenomenon That Can Occur After Death.

Postmortem tanning, previously referred to as either postmortem suntan or postmortem sunburn, presents as hyperpigmentation of sun-exposed uncovered skin. It most commonly occurs in decedents who remain in an environment in which the ambient temperature is either warm or hot; the areas of the corpse that are exposed to the sun develop hyperpigmentation. This postmortem change usually appears in the fresh (first) stage of decomposition. We describe three decedents who developed postmortem tanning. One of the women has an extensive severe darkening of her skin in the distribution where her skin was exposed to sunlight. The second woman had a localized band of pronounced tanning on her lower abdomen; associated early decomposition had occurred, including skin slippage and possible marbling of the superficial veins, at the location of the tanning. The third case, a young man, showed the concurrent presence of keratosis pilaris on his extensor arms that were affected by the tanning. In contrast to livor mortis, postmortem tanning occurs on the skin that is located on the non-dependent side of the body, those areas most apt to be exposed to sunlight. In living individuals, melanogenesis-associated tanning is usually an oxygen-dependent process. In decedents, blood flow and oxygen delivery to the skin that becomes darkened/hyperpigmented is not mandatory. Areas for future investigation include description of the histologic appearance of the tanned skin in comparison to adjacent, non-tanned skin, the incidence of postmortem tanning, the factors that may accelerate or decelerate the occurrence of postmortem tanning, and the possible correlation of the appearance of postmortem tanning as a feature that can be used to reveal information for estimating the postmortem interval.