ICD-10-CM > S00-T88 > T20-T25 > T25 > T25.4 > T25.43 > T25.439 T25.439 Corrosion of unspecified degree of unspecified toe(s) (nail) Non-Billable/Non-Specific Codes T25.439A..., initial encounterT25.439D..., subsequent encounterT25.439S..., sequela