1642 (pre): Megetius’ Flaming Vertebra
In Ezekiel de Castro's 1642 book Ignis Lambens -- which is largely about people with light coming from their skin, by the way -- is a short account about a man named Alexandrini Medici Megetij. From what we are told, a flame was seen to project from the area of the base of his spine by two witnesses, identified as Simplitij and Philatei.
In 1745, author Paul Rolli mentioned this event in his own study of strange fires, and seems to have added two new details that he doesn't give a source for. According to Rolli, the flame was proceed by a pain in the lower back -- which is not reported by de Castro -- and the flame was said to "burn the eyes" of the witnesses, which may mean it was hard to look at, or that its smoke irritated eyes, or something completely unguessible. But this 'fact' was also not reported by de Castro, and Rolli doesn't mention where it came from... so it's an unreliable addition.
From Latin to English... Almost
The most quoted version of this account comes from Paul Rolli's 1745 study of spontaneous combustion, but some odd changes occurred when Rolli did his translation of the original Latin. Name changes are generally predictible -- Simplitij's name became Simplicius, and Philatei's name became Philaseus -- but a problem occurred when Alexandrini Medici Megetij was translated: he became "Alexandrinus Megetius, a Physician." This is because 'medici' is latin for 'doctor'; but Medici is also a family name, which is what it seems to be in this case since it was presented in the original text capitalized and as a middle name. So the name probably should have been rendered simply as Alexandrinus Medici Megetius.
Due to this logic error, there are still sources that report "Alexandrinus Megetius" as a doctor or physician, and probably always will be.