ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.4 > T23.42 > T23.422 T23.422 Corrosion of unspecified degree of single left finger (nail) except thumb Non-Billable/Non-Specific Codes T23.422A..., initial encounterT23.422D..., subsequent encounterT23.422S..., sequela