ICD-10-CM > S00-T88 > T33-T34 > T34 > T34.8 > T34.81 > T34.819 T34.819 Frostbite with tissue necrosis of unspecified ankle Non-Billable/Non-Specific Codes T34.819A..., initial encounterT34.819D..., subsequent encounterT34.819S..., sequela