2026 ICD-10-CM Diagnosis Code C73Malignant neoplasm of thyroid gland

ICD-10-CM Codes›C00–D49›C73-C75›C73

ICD-10-CM C73
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C73 is a billable ICD-10-CM diagnosis code for malignant neoplasm of thyroid gland. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 643 through 645. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Endocrine system cancers - thyroid.

Code Identity

ICD-10-CM Code
C73
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of thyroid gland
Chapter
C73-C75
Malignant neoplasms of thyroid and other endocrine glands

Code Classification

ChapterC00–D49Neoplasms
SectionC73-C75Malignant neoplasms of thyroid and other endocrine glands
CategoryC73Malignant neoplasm of thyroid gland
This CodeC73Malignant neoplasm of thyroid gland

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anaplastic thyroid carcinoma
  • Carcinoma of thyroid
  • Differentiated thyroid carcinoma
  • Diffuse sclerosing papillary thyroid carcinoma
  • Familial nonmedullary primary thyroid carcinoma
  • Familial papillary thyroid carcinoma with renal papillary neoplasia syndrome
  • Follicular neoplasm of thyroid
  • Follicular thyroid carcinoma
  • Hurthle cell carcinoma of thyroid
  • Local recurrence of malignant neoplasm of thyroid
  • Malignant neoplasm of thyroid gland
  • Medullary thyroid carcinoma
  • Metastatic anaplastic thyroid carcinoma
  • Metastatic malignant neoplasm to thyroid gland
  • Mixed follicular and papillary thyroid carcinoma
  • Neoplasm of thyroglossal duct
  • Oxyphilic adenocarcinoma
  • Papillary thyroid carcinoma
  • Papillary thyroid carcinoma with renal papillary neoplasia
  • Primary anaplastic thyroid carcinoma
  • Primary differentiated carcinoma of thyroid gland
  • Primary diffuse sclerosing papillary thyroid carcinoma
  • Primary follicular thyroid carcinoma
  • Primary Hurthle cell carcinoma of thyroid
  • Primary malignant neoplasm of thyroglossal duct
  • Primary malignant neoplasm of thyroid gland
  • Primary medullary thyroid carcinoma
  • Primary mixed follicular and papillary thyroid carcinoma
  • Primary oxyphilic adenocarcinoma
  • Primary papillary thyroid carcinoma
  • Primary papillary thyroid carcinoma with renal papillary neoplasia
  • Primary poorly differentiated carcinoma of thyroid gland
  • Primary undifferentiated carcinoma of thyroid gland

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Use Additional Code

  • code to identify any functional activity

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Adenocarcinoma
      • follicular
        • with papillary
    • Adenocarcinoma
      • follicular
        • moderately differentiated
    • Adenocarcinoma
      • follicular
        • trabecular
    • Adenocarcinoma
      • follicular
        • unspecified site
    • Adenocarcinoma
      • follicular
        • well differentiated
    • Adenocarcinoma
      • Hurthle cell
    • Adenocarcinoma
      • nonencapsulated sclerosing
    • Adenocarcinoma
      • papillary
        • with follicular
    • Adenocarcinoma
      • papillary
        • follicular variant
    • Carcinoma(malignant)
      • C cell
        • unspecified site
    • Carcinoma(malignant)
      • follicular
        • with papillary (mixed)
    • Carcinoma(malignant)
      • follicular
        • moderately differentiated
    • Carcinoma(malignant)
      • follicular
        • pure follicle
    • Carcinoma(malignant)
      • follicular
        • trabecular
    • Carcinoma(malignant)
      • follicular
        • unspecified site
    • Carcinoma(malignant)
      • follicular
        • well differentiated
    • Carcinoma(malignant)
      • Hurthle cell
    • Carcinoma(malignant)
      • medullary
        • with
          • amyloid stroma
            • unspecified site
    • Carcinoma(malignant)
      • nonencapsulated sclerosing
    • Carcinoma(malignant)
      • papillary
        • with follicular (mixed)
    • Carcinoma(malignant)
      • papillary
        • follicular variant
    • Carcinoma(malignant)
      • parafollicular cell
        • unspecified site
    • Carcinoma(malignant)
      • solid
        • with amyloid stroma
          • unspecified site
    • Goiter(plunging) (substernal)
      • cancerous
    • Goiter(plunging) (substernal)
      • malignant
    • Hurthle cell
      • adenocarcinoma
    • Hurthle cell
      • carcinoma
    • Tumor
      • Hurthle cell (benign)
        • malignant
    • Tumor
      • nonencapsulated sclerosing
    • Wuchernde Struma Langhans

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO050
Endocrine system cancers - thyroid
Default principal diagnosis: inpatient Yes · outpatient Yes

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
thyroglossal ductC73C79.89D09.3D34D44.0D49.7
thyroid (gland)C73C79.89D09.3D34D44.0D49.7

Patient EducationClinical

Thyroid Cancer

Thyroid cancer is a cancer that starts in the tissues of the thyroid. Your thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that control the way the body uses energy. These hormones affect nearly every organ in your body and control many of your body's most important functions.

The full article covers:

  • What is thyroid cancer?
  • What are the different types of thyroid cancer?
  • Who is more likely to develop thyroid cancer?
  • What are the symptoms of thyroid cancer?
  • How is thyroid cancer diagnosed?
  • What are the treatments for thyroid cancer?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C73 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
193 Malign neopl thyroid
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C73Overview

Is C73 (Malignant neoplasm of thyroid gland) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of thyroid gland on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C73 group to?

When malignant neoplasm of thyroid gland is the principal diagnosis on an inpatient stay, it groups to MS-DRG 643, 644, 645, with relative weights from 0.7683 to 1.6461 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C73?

Under the General Equivalence Mappings, malignant neoplasm of thyroid gland converts to ICD-9-CM 193 (malign neopl thyroid). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.