Acne is a common reported side effect from finasteride. The acne is caused by an increase in testosterone levels and should subside as the body adjusts. The acne can be anywhere hormone-induced acne is found like the face, upper back, shoulders, etc.
Yes Propceia caused a return of my facial acne after almost eight years without it being a problem. I suspect it may cause acne more often in those who were prone to it as teenagers, but that is just my speculation.