2026 ICD-10-CM Diagnosis Code B58.3Pulmonary toxoplasmosis
ICD-10-CM Codes›A00–B99›B50-B64›B58
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B58.3 is a billable ICD-10-CM diagnosis code for pulmonary toxoplasmosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 177 through 179, 791, 793, 974 through 976. 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 110 closely related codes. Coders also document this condition as pneumonia due to parasitic infestation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections; and Pneumonia (except that caused by tuberculosis).
For Medicare Advantage risk adjustment, B58.3 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
B58.3 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.
- Pneumonia due to parasitic infestation
- Toxoplasma pneumonia
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Pneumonitis (acute) (primary) See Also: Pneumonia; J98.4
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Toxoplasma Pneumonia
pneumonia caused by the parasite toxoplasma gondii. it usually presents as an opportunistic infection in immunocompromised patients, especially patients with aids. it is rare in immunocompetent individuals. signs and symptoms include cough, fever, and dyspnea.
Patient EducationClinical
Lung Diseases
When you breathe, your lungs take in oxygen from the air and deliver it to the bloodstream. The cells in your body need oxygen to work and grow. During a normal day, you breathe nearly 25,000 times. People with lung disease have difficulty breathing. Millions of people in the U.S. have lung disease.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B58.3 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B58.3Overview
What is the ICD-10 code for pulmonary toxoplasmosis?
The ICD-10-CM code for pulmonary toxoplasmosis is B58.3 (sometimes written as B583). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is B58.3 (Toxoplasmosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pulmonary toxoplasmosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does B58.3 group to?
When pulmonary toxoplasmosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 177, 178, 179, 791, 793, 974, 975, 976, with relative weights from 0.7550 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B58.3 a CC or MCC?
CMS lists B58.3 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 110 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B58.3?
Under the General Equivalence Mappings, pulmonary toxoplasmosis converts to ICD-9-CM 130.4 (toxoplasma pneumonitis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is B58.3?
B58.3 (pulmonary toxoplasmosis) 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 B58.3 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B58.3 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.
