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C73 ICD-10-CM Code: Malignant neoplasm of thyroid gland

Compare with another codeCheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 use-additional code
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 12 · RxHCC V08 category 22

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 011 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH MCC (MDC PRE)
  • MS-DRG 012 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITH CC (MDC PRE)
  • MS-DRG 013 — TRACHEOSTOMY FOR FACE, MOUTH AND NECK DIAGNOSES OR LARYNGECTOMY WITHOUT CC/MCC (MDC PRE)
  • MS-DRG 643 — ENDOCRINE DISORDERS WITH MCC (MDC 10)
  • MS-DRG 644 — ENDOCRINE DISORDERS WITH CC (MDC 10)
  • MS-DRG 645 — ENDOCRINE DISORDERS WITHOUT CC/MCC (MDC 10)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 23 — Prostate, Breast, and Other Cancers and Tumors

Other models: CMS-HCC V22 HCC 12 · RxHCC V08 HCC 22

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for C73 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code to identify any functional activity

Coder workflow for C73

MedCoder structured workflow — derived from this code’s own official record

Before you code C73

  1. Confirm the documented site and behavior (this code’s block classifies malignant neoplasms), whether the site is primary or secondary, and whether the malignancy is current or a personal history: a previously excised malignancy with no further treatment and no evidence of disease is history, not current disease. Verify the site against the Table of Neoplasms. Neoplasm chapter guidelines (Guidelines I.C.2.a, I.C.2.d, I.C.2.m).

    See the Table of Neoplasms entries · Guide: Active cancer vs history of cancer →

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Anatomical site
At the most specific level the record states; a site the classification separates cannot be assumed from a procedure or a measurement.
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
Behavior and current-versus-history status
Malignant, in situ, benign or uncertain; primary or secondary; current disease or personal history (Guidelines I.C.2.m).

Official instructions as workflow

  • Use Additional Code — after identifying C73(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with C73 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with C73?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Coding context

The comparisons, hierarchy, index entries, guidelines, relationships, risk-adjustment and coverage context a coder commonly needs. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Malignant neoplasm of thyroid gland is a billable ICD-10-CM diagnosis code (C73).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (30)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Neoplasm Table Sites (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Anatomical sites from the official ICD-10-CM Table of Neoplasms that map to this code, with the matching behavior column.

  • Neoplasm, neoplastic, thyroglossal duct — Malignant, Primary
  • Neoplasm, neoplastic, thyroid (gland) — Malignant, Primary

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name C73 or its code family, from the CMS ICD-10-CM tabular instructional notes, the CMS Table of Neoplasms and the CMS Table of Neoplasms (site match derived from the code title). Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: C75 — Malignant neoplasm of other endocrine glands and related structures.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 5 Same-site neoplasm codes: C79.89 — Secondary malignant neoplasm of other specified sitesCompare C73 vs C79.89 →, D09.3 — Carcinoma in situ of thyroid and other endocrine glandsCompare C73 vs D09.3 →, D34 — Benign neoplasm of thyroid glandCompare C73 vs D34 →, D44.0 — Neoplasm of uncertain behavior of thyroid glandCompare C73 vs D44.0 →, D49.7 — Neoplasm of unspecified behavior of endocrine glands and other parts of nervous systemCompare C73 vs D49.7 →.

These codes represent related neoplasm behaviors affecting the same anatomic site.

Referenced by 1 Screening & history code: Z85.850 — Personal history of malignant neoplasm of thyroidCompare C73 vs Z85.850 →.

These codes represent screening tests and history codes that refer to this active disease condition.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 6 MS-DRGs: DRG 011 (MDC PRE), DRG 012 (MDC PRE), DRG 013 (MDC PRE), DRG 643 (MDC 10), DRG 644 (MDC 10), DRG 645 (MDC 10).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NEO050 — Endocrine system cancers - thyroid (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Prostate, Breast, and Other Cancers and Tumors) for risk-adjusted payment.

C69.52 — Malignant neoplasm of left lacrimal gland and duct, C69.60 — Malignant neoplasm of unspecified orbit, C69.61 — Malignant neoplasm of right orbit, C69.62 — Malignant neoplasm of left orbit, C69.80 — Malignant neoplasm of overlapping sites of unspecified eye and adnexa, C69.81 — Malignant neoplasm of overlapping sites of right eye and adnexa, C69.82 — Malignant neoplasm of overlapping sites of left eye and adnexa, C69.90 — Malignant neoplasm of unspecified site of unspecified eye, C69.91 — Malignant neoplasm of unspecified site of right eye, C69.92 — Malignant neoplasm of unspecified site of left eye, C75.0 — Malignant neoplasm of parathyroid gland, C75.4 — Malignant neoplasm of carotid body, C75.5 — Malignant neoplasm of aortic body and other paraganglia, C75.8 — Malignant neoplasm with pluriglandular involvement, unspecified, C75.9 — Malignant neoplasm of endocrine gland, unspecified, C76.0 — Malignant neoplasm of head, face and neck, C76.1 — Malignant neoplasm of thorax, C76.2 — Malignant neoplasm of abdomen, C76.3 — Malignant neoplasm of pelvis, C76.40 — Malignant neoplasm of unspecified upper limb, +213 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic, Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers, Lung and Other Severe Cancers, Lymphoma and Other Cancers, Bladder, Colorectal, and Other Cancers

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Endocrine system cancers - thyroid).

D09.3 — Carcinoma in situ of thyroid and other endocrine glands, E31.22 — Multiple endocrine neoplasia [MEN] type IIA, E31.23 — Multiple endocrine neoplasia [MEN] type IIB

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Carcinoma”, “Tumor”, “Adenocarcinoma”; these codes share that main term but sit in a different category of the Tabular List.

C50.92 — Malignant neoplasm of breast of unspecified site, male (lipid-rich, male), C53.9 — Malignant neoplasm of cervix uteri, unspecified (solid, microinvasive, unspecified site), C54.9 — Malignant neoplasm of corpus uteri, unspecified (Müllerian, mixed, unspecified site), C56 — Malignant neoplasm of ovary (granulosa cell), C56.9 — Malignant neoplasm of unspecified ovary (yolk sac, unspecified site, female), C58 — Malignant neoplasm of placenta (chorionic, unspecified site, female), C61 — Malignant neoplasm of prostate (duct, unspecified site, male), C62.90 — Malignant neoplasm of unspecified testis, unspecified whether descended or undescended (yolk sac, unspecified site, male), C64 — Malignant neoplasm of kidney, except renal pelvis (Wilms'), C71.9 — Malignant neoplasm of brain, unspecified (neuroectodermal, primitive, unspecified site), C74.0 — Malignant neoplasm of cortex of adrenal gland (adrenal cortical), C75.0 — Malignant neoplasm of parathyroid gland (water-clear cell), C75.1 — Malignant neoplasm of pituitary gland (basophil, unspecified site), C75.4 — Malignant neoplasm of carotid body (carotid body, malignant), C75.5 — Malignant neoplasm of aortic body and other paraganglia (aortic body, malignant), C79.6 — Secondary malignant neoplasm of ovary (Krukenberg's), C7A.00 — Malignant carcinoid tumor of unspecified site (carcinoid, malignant), C7A.010 — Malignant carcinoid tumor of the duodenum (carcinoid, malignant, duodenum), C7A.011 — Malignant carcinoid tumor of the jejunum (carcinoid, malignant, jejunum), C7A.012 — Malignant carcinoid tumor of the ileum (carcinoid, malignant, ileum), +158 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Iron Panel, Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of C73 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run C73 with this related code in Claim Check

Hierarchy

Same site

Referenced by Excludes1 notes

Referenced by Same-site neoplasm codes

Referenced by Screening & history codes MedCoder-derived

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 23 — Prostate, Breast, and Other Cancers and Tumors [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • Pre-MDC[MDC crossing]: “Pre-MDC — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 175 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 10 — Endocrine, Nutritional and Metabolic Diseases and Disorders[MDC crossing]: “Endocrine, Nutritional and Metabolic Diseases and Disorders — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,013 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Neoplasm sites

  • Neoplasm, neoplastic, thyroglossal duct — Neoplasm, neoplastic, thyroglossal duct — Malignant, Primary [Neoplasm table]: “Neoplasm, neoplastic, thyroglossal duct (Malignant, Primary)”— CMS Table of Neoplasms · icd10cm-fy2027
  • Neoplasm, neoplastic, thyroid (gland) — Neoplasm, neoplastic, thyroid (gland) — Malignant, Primary [Neoplasm table]: “Neoplasm, neoplastic, thyroid (gland) (Malignant, Primary)”— CMS Table of Neoplasms · icd10cm-fy2027

Index entries (30)

  • Adenocarcinoma, follicular, moderately differentiated[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, follicular, trabecular[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, follicular, unspecified site[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, follicular, well differentiated[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, follicular, with papillary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, Hurthle cell[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, nonencapsulated sclerosing[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Adenocarcinoma, papillary, follicular variant[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 22 more

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Deep reference

Published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

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 20, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "C73 — Malignant neoplasm of thyroid gland." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/c73-malignant-neoplasm-of-thyroid-gland

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Malignant neoplasm of thyroid gland

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.