ICD-10-CM > S00-T88 > T20-T25 > T21 > T21.4 > T21.40 T21.40 Corrosion of unspecified degree of trunk, unspecified site Non-Billable/Non-Specific Codes T21.40XA..., initial encounterT21.40XD..., subsequent encounterT21.40XS..., sequela