The process of applying for disability benefits can be lengthy. Because of this, the Social Security Administration has a list of Compassionate Allowances (CAL). This is essentially the fast track to disability benefits. When a claimant has a condition that is one of those listed under compassionate allowances, the claimant is automatically approved. This allows the SSA to quickly identify those people who undoubtedly have a disability which prevents them from working in any form and the claimant can receive benefits shortly after applying.
Because the disability claims departments are usually overloaded and because medical records can take months for your doctors to submit, it is helpful if you can submit some medical records (such as a biopsy report if you have cancer) with your application that clearly identifies your condition as one of the compassionate allowances. You can also state this on your application but you do need the evidence to back it up.
Some conditions automatically qualify a claimant for compassionate allowance benefits. Others will qualify you as long as your condition also meets other criteria. Potentially fatal illnesses do not necessarily qualify a person for a compassionate allowance. For a list of conditions that qualify for compassionate allowance click here.
Source: https://disabilityjudges.com/articles/disability-compassionate-allowances