C55 vs Z85.42

C55 (Malignant neoplasm of uterus, part unspecified) compared with Z85.42 (Personal history of malignant neoplasm of other parts of uterus), from the official CMS tabular data.

Summary

Z85.42 is the personal-history or screening code for the active disease C55 names, so the two are not interchangeable.

MedCoder-derived

What is different?

The conditions named and chapter.C55 is “Malignant neoplasm of uterus, part unspecified”; Z85.42 is “Personal history of malignant neoplasm of other parts of uterus”. C55 sits in C00-D49 — Neoplasms; Z85.42 in Z00-Z99 — Factors influencing health status and contact with health services.

Registry fact

Can these codes be reported together?

Not for the same condition.Z85.42 is the personal-history or screening code for the active disease C55 names. Site match derived from the code’s own title against the CMS/CDC Table of Neoplasms. A personal-history code describes a condition that no longer exists and is no longer being treated, so it is not interchangeable with the active-disease code.

MedCoder-derivedGuide: History codes (Z codes)

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.

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?

Yes.History or screening versus active disease. Z85.42 is the personal-history or screening code for the active disease C55 names.

MedCoder-derivedGuide: History codes (Z codes)

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?

Review

Condition lifecycle relationship

Z85.42

Personal history of malignant neoplasm of other parts of uterus

↔

C55

Malignant neoplasm of uterus, part unspecified

What we found

History or screening versus active disease.Z85.42 is the personal-history or screening code for the active disease C55 names.

Site match derived from the code’s own title against the CMS/CDC Table of Neoplasms. A personal-history code describes a condition that no longer exists and is no longer being treated, so it is not interchangeable with the active-disease code.

What to review

Report the history code when the condition no longer exists and is no longer treated; report the active-disease code while it is.

Guide: History codes (Z codes)Check these on a claim

Why it matters

A personal-history code describes a condition that no longer exists and is no longer being treated, so it is not interchangeable with the active-disease code for the same site.

Source / rule

CMS Table of Neoplasms (site match derived from the code title)

Side by side

	C55Malignant neoplasm of uterus, part unspecified	Z85.42Personal history of malignant neoplasm of other parts of uterus
Billing status	Billable	Billable
Classification	C00-D49 — Neoplasms	Z00-Z99 — Factors influencing health status and contact with health services
Definition	Malignant neoplasm of uterus, part unspecified is a billable ICD-10-CM diagnosis code (C55).	Personal history of malignant neoplasm of other parts of uterus is a billable ICD-10-CM diagnosis code (Z85.42).
Includes	malignant neoplasm of skin of female genital organs	—
Code first	—	any follow-up examination after treatment of malignant neoplasm (Z08)
Use additional code	—	code to identify: alcohol use and dependence (F10.-) exposure to environmental tobacco smoke (Z77.22)

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