2026 ICD-10-CM Diagnosis Code D04.21Carcinoma in situ of skin of right ear and external auricular canal

Billable — Valid for Submission
Not Chronic

ICD-10-CM D04.21

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

D04.21 is a billable ICD-10-CM diagnosis code for carcinoma in situ of skin of right ear and external auricular canal. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 606 through 607. Coders also document this condition as carcinoma in situ of skin of ear. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Skin cancers - all other types.

Code Identity

ICD-10-CM Code

D04.21

Billable Status

Yes — Valid for Submission

Code Describes

Carcinoma in situ of skin of right ear and external auricular canal

Short Description

Ca in situ skin of right ear and external auricular canal

Parent Code

D04.2

Carcinoma in situ of skin of ear and external auricular canal

Code Classification

ChapterC00–D49Neoplasms

SectionD00-D09In situ neoplasms

CategoryD04Carcinoma in situ of skin

This CodeD04.21Carcinoma in situ of skin of right ear and external auricular canal

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

Carcinoma in situ of skin of ear
Carcinoma in situ of skin of right ear
Squamous cell carcinoma in situ of skin of ear
Squamous cell carcinoma in situ of skin of right ear

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

Table of NeoplasmsClinical

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

Filter table of neoplasms:

Site	Malig. Primary	Malig. Secondary	Ca in situ	Benign	Uncertain	Unspec.
auditory	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
auditory › canal (external) (skin)	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
auricle, ear [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
auricular canal (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
canal › auditory (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
canal › auricular (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
concha [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear] › auricle or auris [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear] › canal, external [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear] › external meatus [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear] › lobule [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
ear (external) [See Also: Neoplasm, skin, ear] › skin	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
earlobe	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
external	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
external › meatus (ear) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
helix [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
meatus external (ear) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
pinna (ear) NEC [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › auditory canal (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › auricle (ear) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › auricular canal (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › concha [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › ear (external)	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › helix [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › meatus, acoustic (external) [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › pinna [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
skin NOS › tragus [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2
tragus [See Also: Neoplasm, skin, ear]	C44.20	C79.2	D04.2	D23.2	D48.5	D49.2

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.

Convert D04.21 to ICD-9-CMHistory

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

ICD-9-CM

232.2 Ca in situ skin ear

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 D04.21Overview

Is D04.21 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report carcinoma in situ of skin of right ear and external auricular canal on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D04.21 group to?

When carcinoma in situ of skin of right ear and external auricular canal is the principal diagnosis on an inpatient stay, it groups to MS-DRG 606, 607, with relative weights from 0.9064 to 1.5132 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of D04.21?

Under the General Equivalence Mappings, carcinoma in situ of skin of right ear and external auricular canal converts to ICD-9-CM 232.2 (ca in situ skin ear). The mapping is approximate, so confirm the match fits the documentation.

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.

Indicator	Meaning	CMS pays CC/MCC DRG
Y	Diagnosis was present at the time of inpatient admission	Yes
N	Diagnosis was not present at the time of admission	No
U	Documentation is insufficient to determine	No
W	Clinically undetermined	Yes
1	Unreported, exempt from POA reporting	No