What is ICD-10 code C72.1?

C72.1 is the ICD-10-CM diagnosis code for Malignant neoplasm of cauda equina. A malignant (cancerous) tumor that develops in the cauda equina, which is the bundle of nerve roots at the lower end of the spinal cord. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C72.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C72.1 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. C72.1 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. C72.1 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.

Which HCC does C72.1 map to under V28?

C72.1 maps to CMS-HCC V28 HCC 20 (Lung and Other Severe Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C72.1: Malignant neoplasm of cauda

C72.1 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupC72.1

Effective 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)

C72.1

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

Malignant neoplasm of cauda equina

A malignant (cancerous) tumor that develops in the cauda equina, which is the bundle of nerve roots at the lower end of the spinal cord.

Buddy Insight

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 009

HHS-HCC 009 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 22

Prostate, Breast, Bladder, an...

Code-level coefficient reference

Code Book Path

Official

C72Malignant neoplasm of spinal cord, cranial nerves and other parts of central nervous system C72.1Malignant neoplasm of cauda equina

Inclusion Terms

Official

No inclusion terms are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Excludes 2

Official

No Excludes 2 notes are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Related Codes

Official

C72.0Malignant neoplasm of spinal cord C72.2Malignant neoplasm of olfactory nerve C72.3Malignant neoplasm of optic nerve C72.4Malignant neoplasm of acoustic nerve C72.5Malignant neoplasm of other and unspecified cranial nerves

Includes

Official

No Includes notes are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Excludes 1

Official

malignant neoplasm of meninges (C70.-)Inherited from C72
malignant neoplasm of peripheral nerves and autonomic nervous system (C47.-)Inherited from C72

Code First

Official

No Code First sequencing instructions are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C72.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Pathology confirmation of malignancy with histological type

Documentation specifically identifying the cauda equina as the tumor location (not conus medullaris or lumbar spinal cord)

Neurological examination findings including lower extremity function and sphincter control

Confirmation this is a primary malignancy, not metastatic disease

MEAT Support

HCC Buddy guidance

Pathology confirmation of malignancy with histological type

Documentation specifically identifying the cauda equina as the tumor location (not conus medullaris or lumbar spinal cord)

Neurological examination findings including lower extremity function and sphincter control

Confirmation this is a primary malignancy, not metastatic disease

Audit Caution

HCC Buddy guidance

Confusing cauda equina location with lower spinal cord — the cauda equina begins below the conus medullaris at L1-L2

Failing to distinguish primary malignancy from metastatic disease involving the cauda equina region

Not separately coding cauda equina syndrome (G83.4) when present as a manifestation

Using unspecified spinal cord code C72.0 when cauda equina is specifically documented

Common Mistakes

HCC Buddy guidance

C72.0 — Malignant neoplasm of spinal cord: The spinal cord ends at approximately L1-L2; tumors below this level involve the cauda equina, not the cord itself

C41.2 — Malignant neoplasm of vertebral column: Bone tumors of the spine are coded differently from nerve root tumors

D33.4 — Benign neoplasm of spinal cord: Ependymomas of the cauda equina may be benign; verify malignancy status

G83.4 — Cauda equina syndrome: This is the clinical syndrome, not the neoplasm; code both when applicable

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C72.1 an HCC code?

Yes. C72.1 (Malignant neoplasm of cauda equina) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C72.1 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C72.1
Description: Malignant neoplasm of cauda equina
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

ESRDHCC 10, Lymphoma and Other Cancers

Not separately weighted

RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C72.1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C72.1

For C72.1, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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What This Code Means

C72.1 is the ICD-10-CM diagnosis code for malignant neoplasm of cauda equina. A malignant (cancerous) tumor that develops in the cauda equina, which is the bundle of nerve roots at the lower end of the spinal cord. C72.1 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, C72.1 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C72.1; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This code is specific to the cauda equina location; do not use for other spinal cord tumors. For C72.1, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for C72.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code is specific to the cauda equina location; do not use for other spinal cord tumors
•Verify histology documentation and ensure this is confirmed as malignant neoplasm, not benign or uncertain behavior

Clinical Significance

Malignant neoplasm of the cauda equina affects the bundle of nerve roots extending below the spinal cord terminus, potentially causing cauda equina syndrome with bowel/bladder dysfunction, saddle anesthesia, and lower extremity weakness. Accurate coding is critical as this diagnosis drives complex surgical planning and long-term rehabilitation needs. The specific anatomical distinction from spinal cord tumors matters for treatment approach and prognosis.

Documentation Requirements

✓Pathology confirmation of malignancy with histological type
✓Documentation specifically identifying the cauda equina as the tumor location (not conus medullaris or lumbar spinal cord)
✓Neurological examination findings including lower extremity function and sphincter control
✓Confirmation this is a primary malignancy, not metastatic disease
✓Current treatment phase (active treatment, post-surgical surveillance)

Commonly Confused Codes

•C72.0: Malignant neoplasm of spinal cord: The spinal cord ends at approximately L1-L2; tumors below this level involve the cauda equina, not the cord itself
•C41.2: Malignant neoplasm of vertebral column: Bone tumors of the spine are coded differently from nerve root tumors
•D33.4: Benign neoplasm of spinal cord: Ependymomas of the cauda equina may be benign; verify malignancy status
•G83.4: Cauda equina syndrome: This is the clinical syndrome, not the neoplasm; code both when applicable