Pope Leo XII's death: the twist to a longstanding dispute by novel historical documents and paleopathographic analysis.

Although the practice of autopsy on the Pope's corpse was performed from the 16th century, autopsy reports are only rarely analysed, and never with the aim of investigating the real causes of the death from a concomitant medical and historical point of view. Here, for the first time, we report on the discovery of new unpublished documents from the Vatican Secret Archives and their investigation by a scientific and inter-disciplinary approach. This analysis allows us to draw new conclusions on the true cause of Leo XII's mysterious death. His sudden death, that occurred on February 10th, 1829 after a short illness, particularly struck the public. Suspicions of poisoning or surgeon's guilt or inexperience and even the shadow of a venereal disease, contributed to create a "black legend" on his pontificate and death. On the contrary, the present paleopathographic analysis points toward a new conclusion. The regular use of catheterization with a silver syringe provided an easy access for bacterial superinfection, confirmed by the observed early emphysematous stage of the corpse. So, the most substantiated hypothesis concerning the cause of Leo XII's death indicates a severe form of sepsis, exacerbated by a weakened state due to chronic hemorrhoids.