What kind of bathing suit is this?

It's not a wetsuit. I don't know what it's called though! My little sister has one. It's looks like a t-shirt, except with swimming suit material. and then it has either shorts or a bikini bottom. But I DO NOT have the body for a bikini, I HATE one pieces, and I have a really bad skin condition on my upper arm (that part between your shoulder and elbow). Anyway, I want sleeves that will cover that part of my arms, not tight on my stomach, and I'd prefer shorts (well not what guys wear lol) but bikini bottoms would be ok. What's the name for this kind of bathing suit? Thanks! (: