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C77.0 vs C78.6

C77.0 (Secondary and unspecified malignant neoplasm of lymph nodes of head, face and neck) compared with C78.6 (Secondary malignant neoplasm of retroperitoneum and peritoneum), from the official CMS tabular data.

Summary

These codes can be reported together when both conditions are documented, because C78.6 lists C77.0 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named.C77.0 is “Secondary and unspecified malignant neoplasm of lymph nodes of head, face and neck”; C78.6 is “Secondary malignant neoplasm of retroperitoneum and peritoneum”.

Registry fact

Can these codes be reported together?

Yes, when both are documented.C78.6 lists C77.0 under Excludes2: “lymph node metastases (C77.0)”. 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. C77.0 carries 3 Excludes1 notes and C78.6 carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.C78.6’s tabular entry: “lymph node metastases (C77.0)”. The note covers C77.0.

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?

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?

Informational

Excludes2 relationship

C78.6
Secondary malignant neoplasm of retroperitoneum and peritoneum
↔
C77.0
Secondary and unspecified malignant neoplasm of lymph nodes of head, face and neck

What we found

Yes, when both are documented.C78.6 carries an Excludes2 note covering C77.0: “lymph node metastases (C77.0)”

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 Excludes2Check 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

C77.0Secondary and unspecified malignant neoplasm of lymph nodes of head, face and neckC78.6Secondary malignant neoplasm of retroperitoneum and peritoneum
Billing statusBillableBillable
ClassificationC00-D49 — Neoplasms (C00-D49)C00-D49 — Neoplasms (C00-D49)
DefinitionSecondary and unspecified malignant neoplasm of lymph nodes of head, face and neck is a billable ICD-10-CM diagnosis code (C77.0).Secondary malignant neoplasm of retroperitoneum and peritoneum is a billable ICD-10-CM diagnosis code (C78.6).
Includes
Secondary and unspecified malignant neoplasm of supraclavicular lymph nodes
—
Excludes1
malignant neoplasm of lymph nodes, specified as primary (C81-C86, C88, C96.-)
mesentery metastasis of carcinoid tumor (C7B.04)
secondary carcinoid tumors of distant lymph nodes (C7B.01)
secondary carcinoid tumors of liver (C7B.02)
secondary carcinoid tumors of peritoneum (C7B.04)
Excludes2—
lymph node metastases (C77.0)

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.

Edit this comparisonCheck a whole claim

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