2026 ICD-10-CM Diagnosis Code C56.9Malignant neoplasm of unspecified ovary

ICD-10-CM Codes›C00–D49›C51-C58›C56

ICD-10-CM C56.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C56.9 is a billable ICD-10-CM diagnosis code for malignant neoplasm of unspecified ovary. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 736 through 741, 754 through 756. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Female reproductive system cancers - ovary.

Code Identity

ICD-10-CM Code
C56.9
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of unspecified ovary
Short Description
Malignant neoplasm of unspecified ovary
Same as the full description in the CMS dataset.
Parent Code
C56
Malignant neoplasm of ovary

Code Classification

ChapterC00–D49Neoplasms
SectionC51-C58Malignant neoplasms of female genital organs
CategoryC56Malignant neoplasm of ovary
This CodeC56.9Malignant neoplasm of unspecified ovary

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anemia in neoplastic disease
  • Anemia in ovarian carcinoma
  • Carcinoma of ovary, stage 1
  • Carcinoma of ovary, stage 2
  • Carcinoma of ovary, stage 3
  • Carcinoma of ovary, stage 4
  • Carcinosarcoma of ovary
  • Carcinosarcoma of uterine adnexa
  • Choriocarcinoma
  • Choriocarcinoma of ovary
  • Clear cell neoplasm of ovary
  • Clear cell adenocarcinoma of Mullerian origin of ovary
  • Clear cell adenocarcinoma of ovary
  • Cystadenocarcinoma of ovary
  • Embryonal carcinoma
  • Embryonal carcinoma of ovary
  • Endodermal sinus tumor of ovary
  • Endometrioid carcinoma ovary
  • Epithelial ovarian tumor, FIGO stage II
  • Epithelial ovarian tumor, FIGO stage IIC
  • Familial cancer of breast
  • Familial ovarian cancer
  • FIGO ovarian tumor stage finding
  • FIGO stage finding for epithelial tumor of ovary
  • Germ cell tumor of ovary
  • Hereditary breast and ovarian cancer syndrome
  • Invasive ovarian tumor omental implants absent
  • Invasive ovarian tumor omental implants present
  • Malignant Brenner tumor of ovary
  • Malignant dysgerminoma of ovary
  • Malignant epithelial tumor of ovary
  • Malignant germ cell tumor of ovary
  • Malignant granulosa cell tumor of ovary
  • Malignant immature teratoma of ovary
  • Malignant neoplasm involving left fallopian tube by direct extension from ovary
  • Malignant neoplasm involving right fallopian tube by direct extension from ovary
  • Malignant neoplasm involving urinary bladder by direct extension from ovary
  • Malignant neoplasm of ovary
  • Malignant non-dysgerminomatous germ cell tumor of ovary
  • Malignant sex cord tumor of ovary
  • Malignant teratoma
  • Malignant tumor involving an organ by direct extension from ovary
  • Malignant tumor involving left broad ligament by direct extension from ovary
  • Malignant tumor involving rectum by direct extension from ovary
  • Malignant tumor involving right broad ligament by direct extension from ovary
  • Malignant tumor involving uterine cervix by direct extension from ovary
  • Malignant tumor involving uterine corpus by direct extension from ovary
  • Malignant tumor involving vagina by direct extension from ovary
  • Malignant tumor involving vulva by direct extension from ovary
  • Mucinous cystadenocarcinoma of ovary
  • Non-invasive ovarian tumor omental implants absent
  • Non-invasive ovarian tumor omental implants present
  • Polyembryoma
  • Primary carcinosarcoma of ovary
  • Primary carcinosarcoma of uterine adnexa
  • Primary clear cell adenocarcinoma of ovary
  • Primary cystadenocarcinoma of ovary
  • Primary endometrioid carcinoma of ovary
  • Primary high grade serous adenocarcinoma of ovary
  • Primary low grade serous adenocarcinoma of ovary
  • Primary malignant dysgerminoma of ovary
  • Primary malignant granulosa cell tumor of ovary
  • Primary malignant neoplasm of ovary
  • Primary malignant Sertoli-Leydig cell tumor of ovary
  • Primary malignant sex cord tumor of ovary
  • Primary mucinous adenocarcinoma of ovary
  • Primary mucinous carcinoma of uterine adnexa
  • Primary mucinous cystadenocarcinoma of ovary
  • Primary non-gestational choriocarcinoma of ovary
  • Primary serous carcinoma of uterine adnexa
  • Primary serous papillary cystadenocarcinoma ovary
  • Primary small cell neuroendocrine carcinoma of ovary
  • Primary theca steroid producing cell malignant neoplasm of ovary
  • Primary undifferentiated carcinoma of ovary
  • Recurrent ovarian cancer
  • Sarcoma of ovary
  • Serous cystadenoma borderline malignancy of ovary
  • Serous papillary cystadenocarcinoma ovary
  • Small cell carcinoma of ovary
  • Teratoma of ovary
  • Theca steroid producing cell malignant neoplasm of ovary
  • Undifferentiated carcinoma of ovary
  • Yolk sac tumor

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

  • - Cancer - See Also: Neoplasm, by site, malignant;

    • - ovarian - See Also: Neoplasm ovary, malignant; - C56.9

External Cause of Injuries IndexGuidance

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

    • Adenocarcinoma
      • duct
        • unspecified site
          • female
    • Adenocarcinoma
      • papillary
        • serous
          • unspecified site
    • Adenocarcinoma
      • papillocystic
        • unspecified site
    • Adenocarcinoma
      • pseudomucinous
        • unspecified site
    • Adenocarcinoma
      • serous
        • papillary
          • unspecified site
    • Androblastoma
      • malignant
        • unspecified site
          • female
    • Arrhenoblastoma
      • malignant
        • unspecified site
          • female
    • Cancer
      • ovarian
    • Carcinoma(malignant)
      • endometrioid
        • unspecified site
          • female
    • Carcinoma(malignant)
      • Leydig cell (testis)
        • unspecified site
          • female
    • Carcinoma(malignant)
      • papillary
        • serous
          • surface
            • unspecified site
    • Carcinoma(malignant)
      • papillary
        • serous
          • unspecified site
    • Carcinoma(malignant)
      • papillocystic
        • unspecified site
    • Carcinoma(malignant)
      • pseudomucinous
        • unspecified site
    • Carcinoma(malignant)
      • serous
        • papillary
          • unspecified site
    • Carcinoma(malignant)
      • serous
        • surface, papillary
          • unspecified site
    • Carcinoma(malignant)
      • Sertoli cell
        • unspecified site
          • female
    • Cystadenocarcinoma
      • endometrioid
        • unspecified site
          • female
    • Cystadenocarcinoma
      • mucinous
        • papillary
          • unspecified site
    • Cystadenocarcinoma
      • mucinous
        • unspecified site
    • Cystadenocarcinoma
      • papillary
        • mucinous
          • unspecified site
    • Cystadenocarcinoma
      • papillary
        • pseudomucinous
          • unspecified site
    • Cystadenocarcinoma
      • papillary
        • serous
          • unspecified site
    • Cystadenocarcinoma
      • papillary
        • unspecified site
    • Cystadenocarcinoma
      • pseudomucinous
        • papillary
          • unspecified site
    • Cystadenocarcinoma
      • pseudomucinous
        • unspecified site
    • Cystadenocarcinoma
      • serous
        • papillary
          • unspecified site
    • Cystadenocarcinoma
      • serous
        • unspecified site
    • Cystadenoma
      • mucinous
        • borderline malignancy
          • unspecified site
    • Cystadenoma
      • mucinous
        • papillary
          • borderline malignancy
            • unspecified site
    • Cystadenoma
      • papillary
        • borderline malignancy
          • unspecified site
    • Cystadenoma
      • papillary
        • mucinous
          • borderline malignancy
            • unspecified site
    • Cystadenoma
      • papillary
        • pseudomucinous
          • borderline malignancy
            • unspecified site
    • Cystadenoma
      • papillary
        • serous
          • borderline malignancy
            • unspecified site
    • Cystadenoma
      • pseudomucinous
        • borderline malignancy
          • unspecified site
    • Cystadenoma
      • pseudomucinous
        • papillary
          • borderline malignancy
            • unspecified site
    • Cystadenoma
      • serous
        • borderline malignancy
          • unspecified site
    • Cystadenoma
      • serous
        • papillary
          • borderline malignancy
            • unspecified site
    • Dysgerminoma
      • unspecified site
        • female
    • Leydig cell
      • carcinoma
        • unspecified site
          • female
    • Sertoli cell
      • carcinoma
        • unspecified site (male)
          • female
    • Tumor
      • Leydig cell
        • malignant
          • unspecified site
            • female
    • Tumor
      • mucinous of low malignant potential
        • unspecified site
    • Tumor
      • papillary
        • mucinous of low malignant potential
          • unspecified site
    • Tumor
      • papillary
        • serous of low malignant potential
          • unspecified site
    • Tumor
      • polyvesicular vitelline
        • unspecified site
          • female
    • Tumor
      • serous of low malignant potential
        • unspecified site
    • Tumor
      • yolk sac
        • unspecified site
          • female

Clinical ClassificationClinical

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

CCSR NEO033
Female reproductive system cancers - ovary
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Choriocarcinoma

    a malignant metastatic form of trophoblastic tumors. unlike the hydatidiform mole, choriocarcinoma contains no chorionic villi but rather sheets of undifferentiated cytotrophoblasts and syncytiotrophoblasts (trophoblasts). it is characterized by the large amounts of chorionic gonadotropin produced. tissue origins can be determined by dna analyses: placental (fetal) origin or non-placental origin (choriocarcinoma, non-gestational).

  • Choriocarcinoma, Non-gestational

    a highly malignant choriocarcinoma derived from the non-placental origin such as the totipotent cells in the testis, the ovary, and the pineal gland. it produces high levels of chorionic gonadotropin and can metastasize widely through the bloodstream to the lungs, brain, liver, bone, and other viscera by the time of diagnosis.

  • Hereditary Breast and Ovarian Cancer Syndrome

    autosomal dominant hereditary cancer syndrome in which a mutation most often in either brca1 or brca2 is associated with a significantly increased risk for breast and ovarian cancers.

  • Neoplastic Syndromes, Hereditary

    the condition of a pattern of malignancies within a family, but not every individual's necessarily having the same neoplasm. characteristically the tumor tends to occur at an earlier than average age, individuals may have more than one primary tumor, the tumors may be multicentric, usually more than 25 percent of the individuals in direct lineal descent from the proband are affected, and the cancer predisposition in these families behaves as an autosomal dominant trait with about 60 percent penetrance.

Patient EducationClinical

Ovarian Cancer

Cancer is a disease in which abnormal cells in the body grow out of control and form a tumor. Ovarian cancer is a cancerous tumor that forms in the tissues of an ovary. The ovaries are a pair of female reproductive glands that make eggs and female hormones.

The full article covers:

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

Read the full article at MedlinePlus

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

Convert C56.9 to ICD-9-CMHistory

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

ICD-9-CM
183.0 Malign neopl ovary
Approximate The match is approximate rather than exact.

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 C56.9Overview

Is C56.9 (Malignant neoplasm of ovary) a billable code?

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

What MS-DRG does C56.9 group to?

When malignant neoplasm of unspecified ovary is the principal diagnosis on an inpatient stay, it groups to MS-DRG 736, 737, 738, 739, 740, 741, 754, 755, 756, with relative weights from 0.9605 to 3.5745 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C56.9?

Under the General Equivalence Mappings, malignant neoplasm of unspecified ovary converts to ICD-9-CM 183.0 (malign neopl ovary). The mapping is approximate, so confirm the match fits the documentation.

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.