ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.4 > T23.43 > T23.439 T23.439 Corrosion of unspecified degree of unspecified multiple fingers (nail), not including thumb Non-Billable/Non-Specific Codes T23.439A..., initial encounterT23.439D..., subsequent encounterT23.439S..., sequela