2027 ICD-10-CM Diagnosis Code B45.1Cerebral cryptococcosis
ICD-10-CM Codes›A00–B99›B35-B49›B45
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B45.1 is a billable ICD-10-CM diagnosis code for cerebral cryptococcosis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 23 through 24, 97 through 99, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 106 closely related codes. Coders also document this condition as cerebral cryptococcoma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Meningitis.
For Medicare Advantage risk adjustment, B45.1 maps to CMS-HCC Category 6 (Opportunistic Infections) under the V28 model, adding a risk factor of about 0.381 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B45.1 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.
- Cerebral cryptococcoma
- Cerebral cryptococcosis
- Cryptococcal meningitis
- Cryptococcus infection of the central nervous system
- Fungal infection of cerebrum
- Fungal meningitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B45.1: its own notes plus those printed at block B35-B49 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
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.
- Cryptococcal meningitis
- Cryptococcosis meningocerebralis
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name B45.1, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Cryptococcosis, cryptococcus (infection) (neoformans) B45.9
cerebral B45.1
meningitis B45.1
meningocerebralis B45.1
Meningitis (basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic) G03.9
cryptococcal B45.1
Meningoencephalomyelitis See Also: Meningoencephalitis;
Meningomyelitis See Also: Meningoencephalitis;
cryptococcal B45.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Cryptococcosis
fungal infection caused by genus cryptococcus.
Patient EducationClinical
Fungal Infections
If you have ever had athlete's foot or a yeast infection, you can blame a fungus. A fungus is a primitive organism. Mushrooms, mold and mildew are examples. Fungi live in air, in soil, on plants and in water. Some live in the human body. Only about half of all types of fungi are harmful.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B45.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B45.1Overview
What is the ICD-10 code for cerebral cryptococcosis?
The ICD-10-CM code for cerebral cryptococcosis is B45.1 (sometimes written as B451). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B45.1 (Cryptococcosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report cerebral cryptococcosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B45.1 group to?
When cerebral cryptococcosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 24, 98, 99, 23, 97, with relative weights from 1.5249 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B45.1 a CC or MCC?
CMS lists B45.1 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 106 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B45.1?
Under the General Equivalence Mappings, cerebral cryptococcosis converts to ICD-9-CM 117.5 (cryptococcosis) and 321.0 (cryptococcal meningitis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is B45.1?
B45.1 (cerebral cryptococcosis) maps to CMS-HCC Category 6 (Opportunistic Infections), commonly written as HCC 6, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 6 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 5.
Does B45.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B45.1 adds a risk adjustment factor of about 0.381 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.381 to 0.833 depending on the payment segment). HCC 6 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 6 category page.
