ICD-10-CM > S00-T88 > T20-T25 > T21 > T21.7 > T21.75 T21.75 Corrosion of third degree of buttock Non-Billable/Non-Specific Applicable To Corrosion of third degree of anus Codes T21.75XA..., initial encounterT21.75XD..., subsequent encounterT21.75XS..., sequela