ICD-10-CM > S00-T88 > T20-T25 > T25 > T25.5 > T25.59 > T25.599 T25.599 Corrosion of first degree of multiple sites of unspecified ankle and foot Non-Billable/Non-Specific Codes T25.599A..., initial encounterT25.599D..., subsequent encounterT25.599S..., sequela