B39.9
Histoplasmosis, unspecified
B39.9 (also written B399) is a billable ICD-10-CM diagnosis code for histoplasmosis, unspecified. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 7 codes in category B39 (Histoplasmosis). The Alphabetic Index lists it under 3 entries. Its coding notes include a Code first instruction, a Use additional code instruction and 7 Excludes2 entries.
Code first
If the underlying condition listed here is present and known, sequence it first.
Use additional code
Add the listed code as a secondary code, if known.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (7 notes)
- 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)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Infectious Disease, Neoplasms, and Blood-Forming Diseases clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026IRF 60% Rule · with another code
Counts toward the IRF 60 percent rule only in combination, not on its own. CMS lists it together with G02.
Source: CMS IRF Presumptive Compliance-3, FY 2027 IRF PPS final rule files, effective for discharges on or after October 1, 2026Includes
Further defines or gives examples of the content of the category.
Also from chapter/block level (1 note)
- diseases generally recognized as communicable or transmissible
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 3 entries