T24.621S
Corrosion of second degree of right knee, sequela
T24.621S (also written T24621S) is a billable ICD-10-CM diagnosis code for corrosion of second degree of right knee, sequela. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 360 codes in category T24 (Burn and corrosion of lower limb, except ankle and foot). The Alphabetic Index lists it under 1 entry. Its 7th character, S, means sequela. Its coding notes include a Code first instruction, a Use additional code instruction and 4 Excludes2 entries.
7th character
Category T24 requires a 7th character.
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.
Burns are classified by depth, extent and agent. Burns of the same site and side but different degrees take the highest degree. Non-healing burns are coded as acute burns.
Late effects of burns are coded with 7th character S, and a current burn and a sequela of an old burn can be coded together. An external cause code is used with burns.
Code first
If the underlying condition listed here is present and known, sequence it first.
Use additional code
Add the listed code as a secondary code, if known.
- external cause code to identify place (Y92)
Also from chapter/block level (2 notes)
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (2 notes)
- birth trauma (P10-P15)
- obstetric trauma (O70-O71)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
IRF 60% Rule
On the CMS list of diagnoses used to determine presumptive compliance with the IRF 60 percent rule.
Source: CMS IRF Presumptive Compliance-3, FY 2027 IRF PPS final rule files, effective for discharges on or after October 1, 2026Includes
Further defines or gives examples of the content of the category.
Also from chapter/block level (3 notes)
- burns and corrosions of first degree [erythema]
- burns and corrosions of second degree [blisters][epidermal loss]
- burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss]
Notes
Also from chapter/block level (2 notes)
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
Alphabetic Index terms
Terms the official Alphabetic Index lists for T24.621. This code adds the 7th character. 1 entry