T24.731A vs T24.739A

T24.731A (Corrosion of third degree of right lower leg, initial encounter) compared with T24.739A (Corrosion of third degree of unspecified lower leg, initial encounter), from the official CMS tabular data.

Summary

These codes name the same condition on opposite sides of the body, so the documented side decides which one applies.

MedCoder-derived

What is different?

Title wording.The titles differ in one word, “right” (T24.731A) versus “unspecified” (T24.739A): T24.731A is “Corrosion of third degree of right lower leg, initial encounter”; T24.739A is “Corrosion of third degree of unspecified lower leg, initial encounter”.

Registry fact

Can these codes be reported together?

One side per condition.T24.731A and T24.739A name the same condition on opposite sides of the body. Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.

MedCoder-derivedGuide: Laterality coding

Is there an Excludes1 relationship?

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

Official rule

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. T24.731A carries 2 Excludes2 notes and T24.739A carries 2 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

Yes.T24.731A’s title names the condition; T24.739A’s title is the unspecified form (“Corrosion of third degree of unspecified lower leg, initial encounter”).

MedCoder-derivedGuide: Other vs unspecified (NEC vs NOS)

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

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?

Yes.Same condition, opposite side. T24.731A and T24.739A name the same condition on opposite sides of the body.

MedCoder-derivedGuide: Laterality coding

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.

Can these codes be reported together?

Review

Laterality relationship

T24.731A

Right

Corrosion of third degree of right lower leg, initial encounter

↔

T24.739A

Unspecified

Corrosion of third degree of unspecified lower leg, initial encounter

What we found

Same condition, opposite side.T24.731A and T24.739A name the same condition on opposite sides of the body.

Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.

What to review

Report the side the documentation names. Where the code set provides a bilateral code and both sides are documented, use it instead of the pair.

Guide: Laterality coding Check these on a claim

Why it matters

These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.

Source / rule

ICD-10-CM tabular list (laterality variant derived from the code title)

Side by side

	T24.731ACorrosion of third degree of right lower leg, initial encounter	T24.739ACorrosion of third degree of unspecified lower leg, initial encounter
Billing status	Billable	Billable
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 right lower leg, initial encounter is a billable ICD-10-CM diagnosis code (T24.731A).	Corrosion of third degree of unspecified lower leg, initial encounter is a billable ICD-10-CM diagnosis code (T24.739A).
7th character	The appropriate 7th character is to be added to each code from category T24	The appropriate 7th character is to be added to each code from category T24
Includes	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]	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	burn and corrosion of ankle and foot (T25.-) burn and corrosion of hip region (T21.-)	burn and corrosion of ankle and foot (T25.-) burn and corrosion of hip region (T21.-)
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 place (Y92) code from category T31 or T32 to identify extent of body surface involved

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