2026 ICD-10-CM Diagnosis Code B46.0Pulmonary mucormycosis
ICD-10-CM Codes›A00–B99›B35-B49›B46
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B46.0 is a billable ICD-10-CM diagnosis code for pulmonary mucormycosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 791, 793, 867 through 869. 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 14 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections and Other specified and unspecified lower respiratory disease.
For Medicare Advantage risk adjustment, B46.0 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 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B46.0 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 2026.
Source: CMS Payment Year 2026 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.
- Pulmonary mucormycosis
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
pulmonary B46.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Zygomycosis
infection in humans and animals caused by fungi in the class zygomycetes. it includes mucormycosis and entomophthoramycosis. the latter is a tropical infection of subcutaneous tissue or paranasal sinuses caused by fungi in the order entomophthorales. phycomycosis, closely related to zygomycosis, describes infection with members of phycomycetes, an obsolete classification.Mucormycosis
infection in humans and animals caused by any fungus in the order mucorales (e.g., rhizopus; mucor; cunninghamella; apophysomyces; absidia; saksenaea and rhizomucor) there are many clinical types associated with infection including central nervous system, lung, gastrointestinal tract, skin, orbit and paranasal sinuses. in humans, it usually occurs as an opportunistic infection.
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 B46.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B46.0Overview
What is the ICD-10 code for pulmonary mucormycosis?
The ICD-10-CM code for pulmonary mucormycosis is B46.0 (sometimes written as B460). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is B46.0 (Zygomycosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pulmonary mucormycosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B46.0 group to?
When pulmonary mucormycosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 791, 793, 867, 868, 869, with relative weights from 0.7297 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B46.0 a CC or MCC?
CMS lists B46.0 as an MCC (major complication or comorbidity) for FY 2026. 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 14 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B46.0?
Under the General Equivalence Mappings, pulmonary mucormycosis converts to ICD-9-CM 117.7 (zygomycosis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is B46.0?
B46.0 (pulmonary mucormycosis) 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 2026. 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 B46.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B46.0 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.
