2027 ICD-10-CM Diagnosis Code D43.1Neoplasm of uncertain behavior of brain, infratentorial
ICD-10-CM Codes›C00–D49›D37-D48›D43
- Billable — Valid for Submission
- Risk Adjusts — HCC 23
- Chronic Condition
D43.1 is a billable ICD-10-CM diagnosis code for neoplasm of uncertain behavior of brain, infratentorial. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 54 through 55. Coders also document this condition as cerebellar hemangioblastoma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neoplasms of unspecified nature or uncertain behavior.
For Medicare Advantage risk adjustment, D43.1 maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors) under the V28 model, adding a risk factor of about 0.186 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
D43.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Cerebellar hemangioblastoma
- Cerebellar liponeurocytoma
- Hemangioblastoma of brainstem
- Hemangioblastoma of central nervous system
- Low grade glioma of cerebellum
- Neoplasm of uncertain behavior of brain stem
- Neoplasm of uncertain behavior of cerebellum
- Neoplasm of uncertain or unknown behavior of brain, infratentorial
- Pilocytic astrocytoma
- Pilocytic astrocytoma of cerebellum
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to D43.1: its own notes plus those printed at D43, block D37-D48, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Neoplasm of uncertain behavior of brain stem
- Neoplasm of uncertain behavior of cerebellum
- Neoplasm of uncertain behavior of fourth ventricle
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- neoplasm of uncertain behavior of peripheral nerves and autonomic nervous system (D48.2)
- neoplasms of unspecified behavior (D49.-)
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name D43.1, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming D43.1: they are not reported together with it, unless the two conditions are unrelated.
- D43.0 Neoplasm of uncertain behavior of brain, supratentorialneoplasm of uncertain behavior of fourth ventricle (D43.1)
Excludes2 1
These codes carry an Excludes2 note naming D43.1: its condition is not part of those codes, and both may be reported when the patient has both.
- D49 Neoplasms of unspecified behavior
Notes 1
These notes mention D43.1.
- Block D37-D48 Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Infratentorial Neoplasm
a benign or malignant neoplasm that occurs in brain parenchymal tissue below the tentorium cerebelli.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| basis pedunculi | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › cerebellopontine angle | C71.6 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › cerebellum NOS | C71.6 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › choroid plexus | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › medulla oblongata | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › midbrain | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › peduncle | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › pons | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › stem | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| brain NEC › ventricle (floor) › fourth | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| cerebellopontine (angle) | C71.6 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| cerebellum, cerebellar | C71.6 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| cerebrum, cerebral (cortex) (hemisphere) (white matter) › peduncle | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| cerebrum, cerebral (cortex) (hemisphere) (white matter) › ventricle › fourth | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| ependyma (brain) › fourth ventricle | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| medulla › oblongata | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| midbrain | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| olive (brain) | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| peduncle, cerebral | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| pons (varolii) | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| pyramid (brain) | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| spine, spinal (column) › bulb | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| stem, brain | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| ventricle (cerebral) (floor) (lateral) (third) › fourth | C71.7 | C79.31 | – | D33.1 | D43.1 | D49.6 |
| vermis, cerebellum | C71.6 | C79.31 | – | D33.1 | D43.1 | D49.6 |
Patient EducationClinical
Brain Diseases
Your brain is the control center of your body. It controls your thoughts, memory, speech, and movement. It regulates the function of many organs. It's part of your nervous system, which also includes your spinal cord and peripheral nerves. The nervous system sends signals between your brain and the rest of the body.
Read the full article at MedlinePlus
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Convert D43.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About D43.1Overview
What is the ICD-10 code for neoplasm of uncertain behavior of brain, infratentorial?
The ICD-10-CM code for neoplasm of uncertain behavior of brain, infratentorial is D43.1 (sometimes written as D431). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is D43.1 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report neoplasm of uncertain behavior of brain, infratentorial on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does D43.1 group to?
When neoplasm of uncertain behavior of brain, infratentorial is the principal diagnosis on an inpatient stay, it groups to MS-DRG 55, 54, with relative weights from 1.0291 to 1.5197 depending on complications. Higher weights mean higher Medicare reimbursement.
Can D43.1 be reported with D48.2?
Not as a rule. The Excludes1 note at D43, which applies to D43.1, lists "neoplasm of uncertain behavior of peripheral nerves and autonomic nervous system (D48.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of D43.1?
Under the General Equivalence Mappings, neoplasm of uncertain behavior of brain, infratentorial converts to ICD-9-CM 237.5 (unc beh neo brain/spinal). The mapping is approximate, so confirm the match fits the documentation.
What HCC is D43.1?
D43.1 (neoplasm of uncertain behavior of brain, infratentorial) maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors), commonly written as HCC 23, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 12 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.
Does D43.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, D43.1 adds a risk adjustment factor of about 0.186 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.186 to 0.237 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, HCC 20, HCC 21, and HCC 22) supersedes it when both are reported. See the full factor table on the HCC 23 category page.
