ICD-10-CM > S00-T88 > T20-T25 > T25 > T25.6 > T25.63 > T25.639 T25.639 Corrosion of second degree of unspecified toe(s) (nail) Non-Billable/Non-Specific Codes T25.639A..., initial encounterT25.639D..., subsequent encounterT25.639S..., sequela