2026 ICD-10-CM Diagnosis Code C43.9Malignant melanoma of skin, unspecified

ICD-10-CM Codes›C00–D49›C43-C44›C43

ICD-10-CM C43.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C43.9 is a billable ICD-10-CM diagnosis code for malignant melanoma of skin, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 595 through 596. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin cancers - melanoma.

Code Identity

ICD-10-CM Code
C43.9
Billable Status
Yes — Valid for Submission
Code Describes
Malignant melanoma of skin, unspecified
Short Description
Malignant melanoma of skin, unspecified
Same as the full description in the CMS dataset.
Parent Code
C43
Malignant melanoma of skin

Code Classification

ChapterC00–D49Neoplasms
SectionC43-C44Melanoma and other malignant neoplasms of skin
CategoryC43Malignant melanoma of skin
This CodeC43.9Malignant melanoma of skin, unspecified

Quality Payment Program MeasuresBilling

Medicare quality measures that can apply when C43.9 is part of the patient record.

Melanoma Reporting

High Priority: YES

Measure Type: Process

Submission Methods: Claims, Registry

Description: Pathology reports for primary malignant cutaneous melanoma that include the pT category, thickness, ulceration and mitotic rate, peripheral and deep margin status and presence or absence of microsatellitosis for invasive tumors.

View Measure

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acral lentiginous malignant melanoma of skin
  • Adverse effect from PUVA photochemotherapy
  • Amelanotic malignant melanoma of skin
  • Balloon cell malignant melanoma
  • Borderline malignant melanoma
  • Carcinomatosis
  • Clark melanoma level 1
  • Clark melanoma level 2
  • Clark melanoma level 3
  • Clark melanoma level 4
  • Clark melanoma level 5
  • Clark melanoma level finding
  • Congenital malignant melanoma
  • Desmoplastic malignant melanoma
  • Donor derived melanoma
  • Familial malignant melanoma of skin
  • Hypomelanosis surrounding malignant melanoma
  • Hypomelanosis surrounding melanocytic neoplasm
  • Lentigo maligna melanoma
  • Local recurrence of malignant melanoma of skin
  • Malignant blue nevus of skin
  • Malignant melanoma
  • Malignant melanoma animal-type
  • Malignant melanoma arising in congenital nevus
  • Malignant melanoma arising in intradermal nevus
  • Malignant melanoma arising in melanocytic nevus
  • Malignant melanoma metastatic to kidney
  • Malignant melanoma metastatic to pancreas
  • Malignant melanoma of head
  • Malignant melanoma of mucous membrane
  • Malignant melanoma of nail apparatus
  • Malignant melanoma of nail bed
  • Malignant melanoma of skin
  • Malignant melanoma with BRAF V600E mutation
  • Malignant neoplasm of nail apparatus
  • Malignant neoplasm of skin caused by radiation
  • Malignant Spitz tumor
  • Materno-fetal metastatic malignant melanoma
  • Melanoma and neural system tumor syndrome
  • Melanoma carcinomatosis
  • Metastatic amelanotic malignant melanoma to skin
  • Metastatic balloon cell malignant melanoma
  • Metastatic desmoplastic malignant melanoma
  • Metastatic lentigo maligna melanoma
  • Metastatic malignant melanoma to digestive organ
  • Metastatic malignant melanoma to skin
  • Metastatic malignant melanoma with diffuse hypermelanosis
  • Metastatic spindle cell melanoma
  • Metastatic superficial spreading melanoma
  • Mucosal lentiginous melanoma
  • Mucosal nodular melanoma
  • Neurotropic malignant melanoma
  • Nevoid melanoma
  • Nodular malignant melanoma of skin
  • Primary acral lentiginous malignant melanoma of skin
  • Primary amelanotic malignant melanoma of skin
  • Primary balloon cell malignant melanoma
  • Primary desmoplastic malignant melanoma
  • Primary lentigo maligna melanoma
  • Primary malignant blue nevus of skin
  • Primary malignant melanoma of skin
  • Primary mucosal nodular melanoma
  • Primary nodular malignant melanoma of skin
  • Primary spindle cell malignant melanoma
  • Primary superficial spreading malignant melanoma of skin
  • PUVA therapy-associated malignant melanoma
  • Spindle cell malignant melanoma
  • Spitz malignant melanoma
  • Superficial spreading malignant melanoma of skin
  • Surgical deep margin involved by malignant melanoma
  • Surgical deep margin involved by malignant neoplasm
  • Surgical deep margin involvement by melanoma cannot be assessed
  • Surgical deep margin uninvolved by malignant melanoma
  • Surgical lateral margin involved by malignant melanoma
  • Surgical lateral margin involvement by melanoma cannot be assessed
  • Surgical lateral margin uninvolved by malignant melanoma
  • Widespread metastatic malignant neoplastic disease

Tabular List NotesGuidance

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

Inclusion Terms

  • Malignant melanoma of unspecified site of skin
  • Melanoma (malignant) NOS

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.

    • Melanoma(malignant)
    • Melanoma(malignant)
      • skin
    • Melanoma(malignant)
      • skin
        • skin NEC

Clinical ClassificationClinical

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

CCSR NEO025
Skin cancers - melanoma
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Mucosal Nodular Melanoma

    nodular melanoma that arises from a mucosal site.

Patient EducationClinical

Melanoma

Melanoma is the most serious type of skin cancer. Often the first sign of melanoma is a change in the size, shape, color, or feel of a mole. Most melanomas have a black or black-blue area. Melanoma may also appear as a new mole. It may be black, abnormal, or "ugly looking."

Read the full article at MedlinePlus

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

Convert C43.9 to ICD-9-CMHistory

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

ICD-9-CM
172.9 Malig melanoma skin NOS
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 C43.9Overview

Is C43.9 (Malignant melanoma of skin) a billable code?

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

What MS-DRG does C43.9 group to?

When malignant melanoma of skin, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 595, 596, with relative weights from 1.0825 to 2.1207 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C43.9?

Under the General Equivalence Mappings, malignant melanoma of skin, unspecified converts to ICD-9-CM 172.9 (malig melanoma skin NOS). 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.