ICD-10-CM > S00-T88 > T20-T25 > T25 > T25.7 > T25.79 > T25.799 T25.799 Corrosion of third degree of multiple sites of unspecified ankle and foot Non-Billable/Non-Specific Codes T25.799A..., initial encounterT25.799D..., subsequent encounterT25.799S..., sequela