ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.5 > T23.51 T23.51 Corrosion of first degree of thumb (nail) Non-Billable/Non-Specific Codes T23.511Corrosion of first degree of right thumb (nail)T23.511A..., initial encounterT23.511D..., subsequent encounterT23.511S..., sequelaT23.512Corrosion of first degree of left thumb (nail)T23.512A..., initial encounterT23.512D..., subsequent encounterT23.512S..., sequelaT23.519Corrosion of first degree of unspecified thumb (nail)T23.519A..., initial encounterT23.519D..., subsequent encounterT23.519S..., sequela