ICD-10-CM > S00-T88 > T20-T25 > T21 > T21.4 > T21.45 T21.45 Corrosion of unspecified degree of buttock Non-Billable/Non-Specific Applicable To Corrosion of unspecified degree of anus Codes T21.45XA..., initial encounterT21.45XD..., subsequent encounterT21.45XS..., sequela