T21.77XD vs T28.8

T21.77XD (Corrosion of third degree of female genital region, subsequent encounter) compared with T28.8 (Corrosion of internal genitourinary organs), from the official CMS tabular data.

Summary

These codes can be reported together when both conditions are documented, because T21.77XD lists T28.8 under Excludes2, which marks them as distinct conditions.

Official rule

What is different?

Title wording and billing status.The titles share “Corrosion of”; T21.77XD says “third degree of female genital region, subsequent encounter” where T28.8 says “internal genitourinary organs”. T28.8 is a non-billable header; T21.77XD is billable.

Registry fact

Can these codes be reported together?

Yes, when both are documented.T21.77XD lists T28.8 under Excludes2: “corrosion of vagina (T28.8)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code.

Official rule

Is there an Excludes2 relationship?

Yes.T21.77XD’s tabular entry: “corrosion of vagina (T28.8)”. The note covers T28.8.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.T28.8 is a non-billable header, but T21.77XD is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

T21.77XD

Corrosion of third degree of female genital region, subsequent encounter

↔

T28.8

Corrosion of internal genitourinary organs

What we found

Yes, when both are documented.T21.77XD carries an Excludes2 note covering T28.8: “corrosion of vagina (T28.8)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2 Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

Section I.A.12.b — Excludes2 · applies to: Excludes2
A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

	T21.77XDCorrosion of third degree of female genital region, subsequent encounter	T28.8Corrosion of internal genitourinary organs
Billing status	Billable	Non-billable header Report instead: T28.8XXA, T28.8XXD, T28.8XXS
Classification	S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)	S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
Definition	Corrosion of third degree of female genital region, subsequent encounter is a billable ICD-10-CM diagnosis code (T21.77XD).	Corrosion of internal genitourinary organs is a non-billable ICD-10-CM category code (T28.8).
7th character	The appropriate 7th character is to be added to each code from category T21	The appropriate 7th character is to be added to each code from category T28
Includes	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	corrosion of vagina (T28.8) burns and corrosion of axilla (T22.- with fifth character 4) burns and corrosion of scapular region (T22.- with fifth character 6) burns and corrosion of shoulder (T22.- with fifth character 5)	—
Code first	(T51-T65) to identify chemical and intent	(T51-T65) to identify chemical and intent
Use additional code	external cause code to identify place (Y92) code from category T31 or T32 to identify extent of body surface involved	external cause code to identify the source and intent of the burn (X00-X19, X75-X77, X96-X98) external cause code to identify place (Y92)

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2026). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources