ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.5 > T23.54 > T23.549 T23.549 Corrosion of first degree of unspecified multiple fingers (nail), including thumb Non-Billable/Non-Specific Codes T23.549A..., initial encounterT23.549D..., subsequent encounterT23.549S..., sequela