ICD-10-CM > S00-T88 > T20-T25 > T23 > T23.4 > T23.40 > T23.409 T23.409 Corrosion of unspecified degree of unspecified hand, unspecified site Non-Billable/Non-Specific Codes T23.409A..., initial encounterT23.409D..., subsequent encounterT23.409S..., sequela