ICD-10-CM > S00-T88 > T20-T25 > T21 > T21.6 > T21.63 T21.63 Corrosion of second degree of upper back Non-Billable/Non-Specific Applicable To Corrosion of second degree of interscapular region Codes T21.63XA..., initial encounterT21.63XD..., subsequent encounterT21.63XS..., sequela