Figuring out the sizing of these Elie Saab jeans?

Last year I thrifted a pair of Elie Saab dark denim jeans that they said were a men's size 42. Well...they're not and I don't think Elie Saab even makes mens clothing, I've looked. So i'm between a size 35 and 36 and these fit pretty snug and long I'd say around 34x34 or 35x34. My question is the tag says 42 and from what I've gathered a size 42 EU for womens is around a size 31-ish. Is the tag wrong or is there something I'm not understanding about women's jeans?