ICD-10-CM > S00-T88 > S00-S09 > S00 > S00.5 > S00.52 > S00.521 S00.521 Blister (nonthermal) of lip Non-Billable/Non-Specific Codes S00.521A..., initial encounterS00.521D..., subsequent encounterS00.521S..., sequela