A circumstance where a substance or organism takes fire and burns without an exogenous source. Spontaneous human combustion differs from preternatural human combustibility in that in the latter, some spark or trivial flame sets the fire and the body tissues, which have a greatly enhanced inflammability, continue to undergo incineration without any external heat source or combustible materials. (Bergman NA. Spontaneous human combustion: its role in literature and science. Pharos 1988;Fall;51(4):18-21).