Usually No Known Cause
Most cases of syringomas are sporadic and there is no known cause. There are some cases which are genetic and so there are some cases in which syringomas run in the family.
I remember reading about a case of eruptive syringomas reported by dermatologist David Herschthal in the Archives of Dermatogy. If I recall this was due to IV valium. However, this report was 30 years ago, so if my facts aren't straight please forgive me.