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T21.40XA ICD-10-CM Code: Corrosion of unspecified degree of trunk, unspecified site, initial encounter

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Official Registry Overview & Definition

Corrosion of unspecified degree of trunk, unspecified site, initial encounter is a billable ICD-10-CM diagnosis code (T21.40A).

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for T21.40XA in the official ICD-10-CM tabular list.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • burns and corrosion of hip region
  • 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]

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code First

Underlying conditions that must be sequenced before this code.

  • (T51-T65) to identify chemical and intent

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • external cause code to identify place (Y92)
  • Use additional code from category T31 or T32 to identify extent of body surface involved

Frequently Compared Codes

The official Excludes notes on T21.40XA name these codes. Each comparison page covers when the two can — or must not — be reported together.

Change history

No changes recorded for this code — unchanged since the FY2016 baseline of the change ledger.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim.

Relationships & Classification

Official ICD-10-CM tabular notes on other codes that name T21.40XA or its code family.

2 Excludes2 notes: T22 (via T21.-), T24 (via T21.-).

Potential MS-DRG Relationships (FY2026)

Not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity.

Named in the grouper logic of 1 MS-DRG: DRG 935 (MDC 22).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INJ019 — Burn and corrosion, initial encounter (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Contextual Map

Every relationship of T21.40XA in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

  • S00-T88 — Chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) (S00-T88) [Hierarchy]
  • T20-T25 — Burns and corrosions of external body surface, specified by site [Hierarchy]

Referenced by Excludes2 notes

  • T22 — Burn and corrosion of shoulder and upper limb, except wrist and hand [Excludes2](via T21.-): “burn and corrosion of interscapular region (T21.-)” · check together
  • T24 — Burn and corrosion of lower limb, except ankle and foot [Excludes2](via T21.-): “burn and corrosion of hip region (T21.-)” · check together

Clinical classification (CCSR)

  • INJ019 — Burn and corrosion, initial encounter [CCSR]

Potential MS-DRG

  • DRG 935 — NON-EXTENSIVE BURNS [MS-DRG]: “NON-EXTENSIVE BURNS (MDC 22)”

MDC crossing · procedures (377)

  • MDC 22 — Burns [MDC crossing]: “Burns — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”
  • 0HR0X72 — Replacement of Scalp Skin with Autologous Tissue Substitute, Cell Suspension Technique, External Approach [Same-MDC procedure]: “Replacement of Scalp Skin with Autologous Tissue Substitute, Cell Suspension Technique, External Approach — grouped in MDC 22, the procedure side of this code's crossing.” · check together
  • 0HR0X73 — Replacement of Scalp Skin with Autologous Tissue Substitute, Full Thickness, External Approach [Same-MDC procedure]: “Replacement of Scalp Skin with Autologous Tissue Substitute, Full Thickness, External Approach — grouped in MDC 22, the procedure side of this code's crossing.” · check together
  • 0HR0X74 — Replacement of Scalp Skin with Autologous Tissue Substitute, Partial Thickness, External Approach [Same-MDC procedure]: “Replacement of Scalp Skin with Autologous Tissue Substitute, Partial Thickness, External Approach — grouped in MDC 22, the procedure side of this code's crossing.” · check together
  • 0HR0XJ3 — Replacement of Scalp Skin with Synthetic Substitute, Full Thickness, External Approach [Same-MDC procedure]: “Replacement of Scalp Skin with Synthetic Substitute, Full Thickness, External Approach — grouped in MDC 22, the procedure side of this code's crossing.” · check together
  • 0HR0XJ4 — Replacement of Scalp Skin with Synthetic Substitute, Partial Thickness, External Approach [Same-MDC procedure]: “Replacement of Scalp Skin with Synthetic Substitute, Partial Thickness, External Approach — grouped in MDC 22, the procedure side of this code's crossing.” · check together
  • and 372 more

Nearest codes (40)

  • T21 — Burn and corrosion of trunk [Sibling]
  • T21.34XD — Burn of third degree of lower back, subsequent encounter [Sibling]
  • T21.34XS — Burn of third degree of lower back, sequela [Sibling]
  • T21.35 — Burn of third degree of buttock [Sibling]
  • T21.35XA — Burn of third degree of buttock, initial encounter [Sibling]
  • T21.35XD — Burn of third degree of buttock, subsequent encounter [Sibling]
  • T21.35XS — Burn of third degree of buttock, sequela [Sibling]
  • T21.36 — Burn of third degree of male genital region [Sibling]
  • and 32 more

Frequently Asked Questions (FAQ) & Clinical Guidance

Does T21.40XA require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T21.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T21.40XA in its code family, with their registry titles.

  • T21.39XA — Burn of third degree of other site of trunk, initial encounter
  • T21.39XD — Burn of third degree of other site of trunk, subsequent encounter
  • T21.39XS — Burn of third degree of other site of trunk, sequela
  • T21.4 — Corrosion of unspecified degree of trunk
  • T21.40 — Corrosion of unspecified degree of trunk, unspecified site
  • T21.40XD — Corrosion of unspecified degree of trunk, unspecified site, subsequent encounter
  • T21.40XS — Corrosion of unspecified degree of trunk, unspecified site, sequela
  • T21.41 — Corrosion of unspecified degree of chest wall
  • T21.41XA — Corrosion of unspecified degree of chest wall, initial encounter
  • T21.41XD — Corrosion of unspecified degree of chest wall, subsequent encounter

View all codes in the T21 family