On an accident by liquid nitrogen--histological changes of skin in cold

Two young researchers were found lying beside 3 Dewar flasks for liquid nitrogen in a cold experimental room of a university. They were sent to a hospital but died 1.5 h after cardiopulmonary resuscitation. One of the cadavers had dark red discoloration of the skin on the left arm at autopsy. By the histological investigation of the discolored region karyopyknosis and vacuolation of the keratinocytes were noticeably observed in the epidermis. In addition, hyperemia and edematous changes were seen. Hemoglobin (Hb) was not immunodetected in the skin tissue except intravascular erythrocytes. Therefore, these histological findings of the discolored skin can indicate that the skin damage was produced by cold due to liquid nitrogen before death. The cause of death was asphyxia due to oxygen deficiency. There were few autopsy findings which showed the participation of liquid nitrogen in the accident. But, the histological findings of the discolored region demonstrate that liquid nitrogen was involved in this accident.