While difficult for many to comprehend, it has been documented in the literature though unsurprisingly is surrounded by lots of controversy, and so whether BIID makes it into the next version of the DSM or not largely depends on further research.
In the meantime, to better understand the condition and see what it's like from a patient's perspective, learn about the ethical issues involved with voluntary amputations, and get some insight into the current science and research behind BIID, check out the link below.
"This Is What It's Like To Be At War With Your Body" by Anil Ananthaswamy (Medium)