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J70.0 vs T66.XXXS

J70.0 (Acute pulmonary manifestations due to radiation) compared with T66.XXXS (Radiation sickness, unspecified, sequela), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes should not be reported together because T66.XXXS’s tabular entry lists J70.0 under Excludes1.

Official rule
What is different?

The conditions named and chapter.J70.0 is “Acute pulmonary manifestations due to radiation”; T66.XXXS is “Radiation sickness, unspecified, sequela”. J70.0 sits in J00-J99 — Diseases of the Respiratory System (J00-J99); T66.XXXS in S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88).

Registry fact

Can these codes be reported together?

No.T66.XXXS’s entry carries an Excludes1 note covering J70.0: “radiation pneumonitis (J70.0)”. Both may be reported only when the documentation shows the two conditions are unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

Yes.T66.XXXS’s tabular entry: “radiation pneumonitis (J70.0)”. The note covers J70.0.

Official ruleGuide: Excludes1 vs Excludes2

Nothing found in 4 other checks; 1 check does not apply
Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. J70.0 carries 2 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

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?

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?

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?

Excludes1 — generally not reported together

Excludes1 conflict

T66.XXXS
Radiation sickness, unspecified, sequela
↔
J70.0
Acute pulmonary manifestations due to radiation

What we found

No — do not report together.T66.XXXS carries an Excludes1 note covering J70.0: “radiation pneumonitis (J70.0)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

What to review

Report one of the two. Both may be reported only when the documentation shows the two conditions are unrelated to each other.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes1 note means the two conditions are not ordinarily reported together for the same encounter, because the classification treats them as mutually exclusive forms of the same condition. The documented exception is when the two conditions are unrelated to each other.

Source / rule

CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Official guidance behind these answers

  • Section I.A.12.a — Excludes1 · applies to: Excludes1

    A type 1 Excludes note is a pure excludes note. It means “NOT CODED HERE!” An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition. An exception to the Excludes1 definition is the circumstance when the two conditions are unrelated to each other. If it is not clear whether the two conditions involving an Excludes1 note are related or not, query the provider. For example, code F45.8, Other somatoform disorders, has an Excludes1 note for "sleep related teeth grinding (G47.63)," because "teeth grinding" is an inclusion term under F45.8. Only one of these two codes should be assigned for teeth grinding. However psychogenic dysmenorrhea is also an inclusion term under F45.8, and a patient could have both this condition and sleep related teeth grinding. In this case, the two conditions are clearly unrelated to each other, and so it would be appropriate to report F45.8 and G47.63 together.

    ICD-10-CM Official Guidelines FY2027

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

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
J70.0

Acute pulmonary manifestations due to radiation

T66.XXXS

Radiation sickness, unspecified, sequela

StatusSame for both
Billable
Excludes1Differs
J70.0

None at this code

T66.XXXS
  • specified adverse effects of radiation, such as:
  • burns (T20-T31)
  • leukemia (C91-C95)
  • radiation gastroenteritis and colitis (K52.0)
  • radiation pneumonitis (J70.0)
  • radiation related disorders of the skin and subcutaneous tissue (L55-L59)
  • sunburn (L55.-)
Excludes2Differs
J70.0
  • asthma (J45.-)
  • malignant neoplasm of bronchus and lung (C34.-)
T66.XXXS

None at this code

Use additional codeDiffers
J70.0
  • code (W88-W90, X39.0-) to identify the external cause
T66.XXXS

None at this code

Code alsoDiffers
J70.0

None at this code

T66.XXXS
  • , if applicable, place of occurrence, such as:
  • highway rest stop (Y92.523)
  • school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
  • service areas as the place of occurrence of the external cause (Y92.52-)
  • single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
  • transport vehicle as the place of occurrence of the external cause (Y92.81-)
CategoryDiffers
J70.0

J70 Respiratory conditions due to other external agents

T66.XXXS

T66 Radiation sickness, unspecified

ChapterDiffers
J70.0

J00-J99 — Diseases of the Respiratory System (J00-J99)

T66.XXXS

S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)

IncludesDiffers
J70.0
  • Radiation pneumonitis
T66.XXXS

None at this code

7th characterDiffers
J70.0

None at this code

T66.XXXS
  • The appropriate 7th character is to be added to code T66

No Code first note at either code.

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. In a row that differs, each code’s own notes are listed under it, and the notes every code shares are listed once beneath them.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources