ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.6 > T23.61 > T23.619 T23.619 Corrosion of second degree of unspecified thumb (nail) Non-Billable/Non-Specific Codes T23.619A..., initial encounterT23.619D..., subsequent encounterT23.619S..., sequela