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ICD-10-CM 2027 diagnosis code

S21.059Open bite of unspecified breast

Not billable — use a more specific codeRequires 7th character

S21.059 is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it and add the required 7th character.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About S21.059

S21.059 is the ICD-10-CM diagnosis code for open bite of unspecified breast. It belongs to category S21 (open wound of thorax), block S20-S29 (injuries to the thorax) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within S21.05, choose S21.059 (unspecified breast) only when documentation doesn't support a more specific option: right breast (S21.051) and left breast (S21.052).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

7th character

The appropriate 7th character is to be added to each code from category S21

Notes that apply from higher levels

Instructions written at a parent level also apply to S21.059.

› From S21.05 Open bite of breast
Excludes1
  • superficial bite of breast (S20.17)
› From S21 Open wound of thorax
Excludes1
  • traumatic amputation (partial) of thorax (S28.1)
Code also
  • any associated injury, such as:
  • injury of heart (S26.-)
  • injury of intrathoracic organs (S27.-)
  • rib fracture (S22.3-, S22.4-)
  • spinal cord injury (S24.0-, S24.1-)
  • traumatic hemopneumothorax (S27.3)
  • traumatic hemothorax (S27.1)
  • traumatic pneumothorax (S27.0)
  • wound infection

Broader instructions also apply from S20-S29 Injuries to the thorax and Chapter 19: Injury, poisoning and certain other consequences of external causes.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about S21.059

Is S21.059 billable?

No. S21.059 is a header code. Report one of its more specific subcodes instead.