2026 ICD-10-CM Diagnosis Code B44.9Aspergillosis, unspecified
ICD-10-CM Codes›A00–B99›B35-B49›B44
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B44.9 is a billable ICD-10-CM diagnosis code for aspergillosis, unspecified. 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 complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 12 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fungal infections.
For Medicare Advantage risk adjustment, B44.9 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
B44.9 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.
- Aspergilloma
- Aspergillosis
- Aspergillosis co-occurrent with human immunodeficiency virus infection
- Chronic mycotic otitis externa
- Chronic otitis externa due to aspergillosis
- Infection by Aspergillus clavatus
- Infection by Aspergillus flavus
- Infection by Aspergillus fumigatus
- Infection by Aspergillus nidulans
- Infection by Aspergillus niger
- Infection caused by Aspergillus awamori
- Infection caused by Aspergillus bouffardii
- Infection caused by Aspergillus caesiellus
- Infection caused by Aspergillus candidus
- Infection caused by Aspergillus carneus
- Infection caused by Aspergillus chevalieri
- Infection caused by Aspergillus clavato-nanica
- Infection caused by Aspergillus conicus
- Infection caused by Aspergillus deflectus
- Infection caused by Aspergillus flavipes
- Infection caused by Aspergillus glaucus
- Infection caused by Aspergillus janus
- Infection caused by Aspergillus maydis
- Infection caused by Aspergillus montevidensis
- Infection caused by Aspergillus niveus
- Infection caused by Aspergillus notatum
- Infection caused by Aspergillus ochraceus
- Infection caused by Aspergillus oryzae
- Infection caused by Aspergillus parasiticus
- Infection caused by Aspergillus penicillioides
- Infection caused by Aspergillus phialiseptus
- Infection caused by Aspergillus repens
- Infection caused by Aspergillus restrictus
- Infection caused by Aspergillus rugulosus
- Infection caused by Aspergillus sclerotiorum
- Infection caused by Aspergillus sulfureus
- Infection caused by Aspergillus sydowi
- Infection caused by Aspergillus taumanii
- Infection caused by Aspergillus terreus
- Infection caused by Aspergillus terricola
- Infection caused by Aspergillus unguis
- Infection caused by Aspergillus ustus
- Infection caused by Aspergillus versicolor
- Infection caused by Aspergillus wentii
- Infection caused by Neosartorya fischeri
- Invasive aspergillosis
- Neonatal infection caused by Aspergillus
- Pulmonary aspergillosis
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Aspergillosis
infections with fungi of the genus aspergillus.Aspergillosis, Allergic Bronchopulmonary
hypersensitivity reaction (allergic reaction) to fungus aspergillus in an individual with long-standing bronchial asthma. it is characterized by pulmonary infiltrates, eosinophilia, elevated serum immunoglobulin e, and skin reactivity to aspergillus antigen.Invasive Pulmonary Aspergillosis
lung infections with the invasive forms of aspergillus, usually after surgery, transplantation, prolonged neutropenia or treatment with high-doses of corticosteroids. invasive pulmonary aspergillosis can progress to chronic necrotizing pulmonary aspergillosis or hematogenous spread to other organs.Neuroaspergillosis
infections of the nervous system caused by fungi of the genus aspergillus, most commonly aspergillus fumigatus. aspergillus infections may occur in immunocompetent hosts, but are more prevalent in individuals with immunologic deficiency syndromes. the organism may spread to the nervous system from focal infections in the lung, mastoid region, sinuses, inner ear, bones, eyes, gastrointestinal tract, and heart. sinus infections may be locally invasive and enter the intracranial compartment, producing meningitis, fungal; cranial neuropathies; and abscesses in the frontal lobes of the brain. (from joynt, clinical neurology, 1998, ch 27, pp62-3)Pulmonary Aspergillosis
infections of the respiratory tract with fungi of the genus aspergillus.Aspergillus
a genus of mitosporic fungi containing about 100 species and eleven different teleomorphs in the family trichocomaceae.
Patient EducationClinical
Aspergillosis
Aspergillosis is a disease caused by a fungus (or mold) called Aspergillus. The fungus is very common in both indoors and outdoors. Most people breathe in the spores of the fungus every day without being affected. But some people get the disease. It usually occurs in people with lung diseases or weakened immune systems.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B44.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B44.9Overview
What is the ICD-10 code for aspergillosis, unspecified?
The ICD-10-CM code for aspergillosis, unspecified is B44.9 (sometimes written as B449). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is B44.9 (Aspergillosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report aspergillosis, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B44.9 group to?
When aspergillosis, unspecified 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 B44.9 a CC or MCC?
CMS lists B44.9 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 12 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B44.9?
Under the General Equivalence Mappings, aspergillosis, unspecified converts to ICD-9-CM 117.3 (aspergillosis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is B44.9?
B44.9 (aspergillosis, unspecified) 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 B44.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B44.9 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.
