My gynecologist confirmed by ultrasound i have a dermoid cyst. he said because it's bigger than 5cm he needs to remove it. is this normal? i'm worried it's cancerous although he said it was benign and "didn't look bad." just nervous!

Surgery is correct: Dermoid cysts are removed as a general rule if >5cm. They are internal growths that form during embryonic development and can contain skin-like tissue and fat; and maybe even bone, hair and nail. They are not cancer, per say, but they are removed because of the potential for becoming infected and the potential for becoming cancer later. Your gynecologist is right to reassure you,and to remove it