What is ICD-10 code C72.20?

C72.20 is the ICD-10-CM diagnosis code for Malignant neoplasm of unspecified olfactory nerve. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C72.20 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C72.20 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C72.20 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C72.20 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for C72.20?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C72.20, V28 maps to Lung and Other Severe Cancers at RAF 0.000 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C72.20?

Verify documentation specifies olfactory nerve involvement; if the site is documented as right or left, use C72.21 or C72.22 instead of the unspecified code This code requires a secondary code for histological type (8th character) to fully specify the malignancy; ensure pathology reports are reviewed for tumor classification Because C72.20 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

C72.20 ICD-10 Code: Malignant neoplasm

ICD-10-CM Code View

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Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupC72.20Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of eye, brain and other parts of central nervous system (C69-C72)

C72.20

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of unspecified olfactory nerve

This code represents a cancer that has developed in the olfactory nerve (the nerve responsible for the sense of smell), but the specific location along the nerve has not been identified. This is a rare type of brain/nerve cancer.

Buddy Insight

Malignant neoplasm of the unspecified olfactory nerve is a rare cancer of cranial nerve I that typically presents as esthesioneuroblastoma (olfactory neuroblastoma).

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

RAF 0.0

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.0

RXHCC

Mapped

HCC 22

Cancer, Other Specified Sites

RAF 0.0

Code Trumping

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Code Book Path

Official

C72Malignant neoplasm of spinal cord, cranial nerves and other parts of central nervous system

C72.2Malignant neoplasm of olfactory nerve

C72.20Malignant neoplasm of unspecified olfactory nerve

Inclusion Terms

Official

Malignant neoplasm of olfactory bulb

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C72.20 in this effective period.

Related Child Codes

Official

C72.21Malignant neoplasm of right olfactory nerve

C72.22Malignant neoplasm of left olfactory nerve

Includes

Official

ICD-10-CM does not list Includes notes for C72.20 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C72.20 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C72.20 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C72.20 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C72.20 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology report confirming malignancy and histological type (most commonly esthesioneuroblastoma)

Laterality — query provider if right or left side is not specified to use C72.21 or C72.22

Kadish staging or modified Kadish staging if available

Extent of disease including any intracranial extension

MEAT Support

HCC Buddy guidance

Pathology report confirming malignancy and histological type (most commonly esthesioneuroblastoma)

Laterality — query provider if right or left side is not specified to use C72.21 or C72.22

Kadish staging or modified Kadish staging if available

Extent of disease including any intracranial extension

Audit Caution

HCC Buddy guidance

Defaulting to unspecified laterality when the documentation clearly states right or left involvement

Confusing esthesioneuroblastoma (olfactory nerve origin) with sinonasal carcinomas (mucosal origin)

Failing to query the provider for laterality — unspecified codes reduce coding specificity

Not reviewing imaging reports that typically specify the laterality even when the clinical note does not

Common Mistakes

HCC Buddy guidance

C72.21/C72.22 — Right/left olfactory nerve: Use these lateralized codes when side is documented instead of unspecified

C30.0 — Malignant neoplasm of nasal cavity: Sinonasal tumors arising from nasal mucosa, not from the olfactory nerve itself

C31.0 — Malignant neoplasm of maxillary sinus: Paranasal sinus tumors may be confused with olfactory nerve tumors due to proximity

D33.3 — Benign neoplasm of cranial nerves: Must confirm malignancy; some olfactory groove meningiomas are benign

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is C72.20 an HCC code?

Yes. C72.20 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

0.000

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.000

RxHCCHCC 22, Cancer, Other Specified Sites

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for C72.20

For C72.20to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C72.20 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

C72.20 is the ICD-10-CM diagnosis code for malignant neoplasm of unspecified olfactory nerve. This code represents a cancer that has developed in the olfactory nerve (the nerve responsible for the sense of smell), but the specific location along the nerve has not been identified. This is a rare type of brain/nerve cancer. C72.20 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of eye, brain and other parts of central nervous system (c69-c72).

Under the CMS-HCC V28 risk adjustment model, C72.20 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, C72.20 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Verify documentation specifies olfactory nerve involvement; if the site is documented as right or left, use C72.21 or C72.22 instead of the unspecified code. Because C72.20 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C72.20 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify documentation specifies olfactory nerve involvement; if the site is documented as right or left, use C72.21 or C72.22 instead of the unspecified code
•This code requires a secondary code for histological type (8th character) to fully specify the malignancy; ensure pathology reports are reviewed for tumor classification

Clinical Significance

Malignant neoplasm of the unspecified olfactory nerve is a rare cancer of cranial nerve I that typically presents as esthesioneuroblastoma (olfactory neuroblastoma). This tumor's proximity to the cribriform plate and anterior cranial fossa makes it particularly dangerous, often requiring combined craniofacial surgical approaches. The 'unspecified' laterality designation indicates incomplete documentation that should prompt a provider query.

Documentation Requirements

✓Pathology report confirming malignancy and histological type (most commonly esthesioneuroblastoma)
✓Laterality — query provider if right or left side is not specified to use C72.21 or C72.22
✓Kadish staging or modified Kadish staging if available
✓Extent of disease including any intracranial extension
✓Current treatment status and modality (surgery, radiation, chemotherapy)

Commonly Confused Codes

•C72.21/C72.22 — Right/left olfactory nerve: Use these lateralized codes when side is documented instead of unspecified
•C30.0 — Malignant neoplasm of nasal cavity: Sinonasal tumors arising from nasal mucosa, not from the olfactory nerve itself
•C31.0 — Malignant neoplasm of maxillary sinus: Paranasal sinus tumors may be confused with olfactory nerve tumors due to proximity
•D33.3 — Benign neoplasm of cranial nerves: Must confirm malignancy; some olfactory groove meningiomas are benign