ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.7 > T23.72 > T23.721 T23.721 Corrosion of third degree of single right finger (nail) except thumb Non-Billable/Non-Specific Codes T23.721A..., initial encounterT23.721D..., subsequent encounterT23.721S..., sequela