2026 ICD-10-CM Diagnosis Code D04.121Carcinoma in situ of skin of left upper eyelid, including canthus

ICD-10-CM Codes›C00–D49›D00-D09›D04

ICD-10-CM D04.121
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D04.121 is a billable ICD-10-CM diagnosis code for carcinoma in situ of skin of left upper eyelid, including canthus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 124 through 125. Coders also document this condition as carcinoma in situ of skin of left upper eyelid. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin cancers - all other types.

Code Identity

ICD-10-CM Code
D04.121
Billable Status
Yes — Valid for Submission
Code Describes
Carcinoma in situ of skin of left upper eyelid, including canthus
Short Description
Ca in situ skin of left upper eyelid, including canthus
Parent Code
D04.12
Carcinoma in situ of skin of left eyelid, including canthus

Code Classification

ChapterC00–D49Neoplasms
SectionD00-D09In situ neoplasms
CategoryD04Carcinoma in situ of skin
This CodeD04.121Carcinoma in situ of skin of left upper eyelid, including canthus

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carcinoma in situ of skin of left upper eyelid
  • Carcinoma in situ of skin of upper eyelid
  • Squamous cell carcinoma in situ of eyelid
  • Squamous cell carcinoma in situ of skin of face
  • Squamous cell carcinoma in situ of skin of left upper eyelid
  • Squamous cell carcinoma in situ of skin of upper eyelid

Clinical ClassificationClinical

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

CCSR NEO028
Skin cancers - all other types
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Skin Cancer

Skin cancer is the most common form of cancer in the United States. The two most common types are basal cell cancer and squamous cell cancer. They usually form on the head, face, neck, hands, and arms. Another type of skin cancer, melanoma, is more dangerous but less common.

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement D04.121 replaces the following previously assigned code(s):

  • D04.12 - Carcinoma in situ of skin of left eyelid, including canthus
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D04.121Overview

Is D04.121 (Carcinoma in situ of skin of left eyelid, including canthus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report carcinoma in situ of skin of left upper eyelid, including canthus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D04.121 group to?

When carcinoma in situ of skin of left upper eyelid, including canthus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 124, 125, with relative weights from 0.7678 to 1.3231 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.