ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.5 > T23.52 > T23.521 T23.521 Corrosion of first degree of single right finger (nail) except thumb Non-Billable/Non-Specific Codes T23.521A..., initial encounterT23.521D..., subsequent encounterT23.521S..., sequela