ICD-10-CM > S00-T88 > S20-S29 > S20 > S20.4 > S20.40 > S20.409 S20.409 Unspecified superficial injuries of unspecified back wall of thorax Non-Billable/Non-Specific Codes S20.409A..., initial encounterS20.409D..., subsequent encounterS20.409S..., sequela