2026 ICD-10-CM Diagnosis Code D84.9Immunodeficiency, unspecified

ICD-10-CM Codes›D50–D89›D80-D89›D84

ICD-10-CM D84.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D84.9 is a billable ICD-10-CM diagnosis code for immunodeficiency, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 814 through 816. 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 44 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.

D84.9 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 47 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 47, ESRD (V21) category 47, ESRD (V24) category 47, and RxHCC Part D (V08) category 99 for payment year 2026.

Code Identity

ICD-10-CM Code
D84.9
Billable Status
Yes — Valid for Submission
Code Describes
Immunodeficiency, unspecified
Short Description
Immunodeficiency, unspecified
Same as the full description in the CMS dataset.
Parent Code
D84
Other immunodeficiencies

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD80-D89Certain disorders involving the immune mechanism
CategoryD84Other immunodeficiencies
This CodeD84.9Immunodeficiency, unspecified

Medicare Risk Adjustment (HCC)Billing

D84.9 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 47
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 47 · ESRD (V21): HCC 47 · ESRD (V24): HCC 47
ESRD V21 weights: 0.097 dialysis, 0.549–0.688 functioning graft · ESRD V24 weights: 0.078 dialysis, 0.523–0.803 functioning graft
Part D (RxHCC)
RxHCC 99 — Immune Disorders
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Adenovirus infection in immunocompromised person
  • Adult-onset immunodeficiency
  • Age-related immunodeficiency
  • Anhidrotic ectodermal dysplasia with immune deficiency
  • Anhidrotic ectodermal dysplasia with immune deficiency due to IKBA gain of function mutation
  • Anhidrotic ectodermal dysplasia with immune deficiency due to IKBKB GOF mutation
  • Centromeric instability of chromosomes 1,9 and 16 and immunodeficiency
  • Congenital anomaly of endocrine ovary
  • Congenital immunodeficiency disease
  • Congenital livedo reticularis
  • Disseminated dermatophytosis
  • Disseminated dermatophytosis due to immunodeficiency
  • Drug-induced immunodeficiency
  • Facial dysmorphism, immunodeficiency, livedo, short stature syndrome
  • Factor I deficiency
  • Iatrogenic immunodeficiency-associated lymphoproliferative disorder
  • Immunodeficiency caused by long term therapeutic use of drug
  • Immunodeficiency disorder
  • Immunodeficiency secondary to chemotherapy
  • Immunodeficiency secondary to corticosteroid
  • Immunodeficiency secondary to neoplasm
  • Immunodeficiency secondary to trauma
  • Immunodeficiency with factor I anomaly
  • Immunodeficiency with thymoma
  • Immuno-osseous dysplasia
  • Immunosuppression
  • Laron syndrome with immunodeficiency
  • Livedo reticularis
  • Lung fibrosis, immunodeficiency, 46,XX gonadal dysgenesis syndrome
  • Microcephaly, normal intelligence and immunodeficiency
  • Oral hairy leukoplakia associated with immunodeficiency
  • Ovarian dysgenesis
  • Patient immunocompromised
  • Patient immunosuppressed
  • Primary immune deficiency disorder
  • Primary immunodeficiency with post-measles-mumps-rubella vaccine viral infection
  • Pure gonadal dysgenesis
  • Pure gonadal dysgenesis 46,XX
  • Roifman syndrome
  • Secondary immune deficiency disorder
  • Susceptibility to viral and mycobacterial infection

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Immunocompromised NOS
  • Immunodeficient NOS
  • Immunosuppressed NOS

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.

CCSR BLD008
Immunity disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Livedo Reticularis

    a condition characterized by a reticular or fishnet pattern on the skin of lower extremities and other parts of the body. this red and blue pattern is due to deoxygenated blood in unstable dermal blood vessels. the condition is intensified by cold exposure and relieved by rewarming.

  • Livedoid Vasculopathy

    a rare cutaneous thrombotic disease due to occlusion of dermal vessels. it is characterized by purpuric maculae and ulcerations especially during summer which form scars called atrophie blanche. it is more associated with other syndromes (e.g., protein c deficiency; hyperhomocysteinemia). livedo reticularis with systemic involvement and stroke is sneddon syndrome.

  • Sneddon Syndrome

    a systemic non-inflammatory arteriopathy primarily of middle-aged females characterized by the association of livedo reticularis, multiple thrombotic cerebral infarction; coronary disease, and hypertension. elevation of antiphospholipid antibody titers (see also antiphospholipid syndrome), cardiac valvulopathy, ischemic attack, transient; seizures; dementia; and chronic ischemia of the extremities may also occur. pathologic examination of affected arteries reveals non-inflammatory adventitial fibrosis, thrombosis, and changes in the media (from jablonski, dictionary of syndromes & eponymic diseases, 2d ed; adams et al., principles of neurology, 6th ed, p861; arch neurol 1997 jan;54(1):53-60). mutations in the cecr1 gene (ada2 protein, human) are associated with sneddon syndrome.

  • Livedo Reticularis

    a recurrent purple discoloration of the skin that does not blanche and is found in a lacy, network pattern, most often in the lower extremities. it may be aggravated by exposure to cold and is classified as idiopathic or secondary. secondary livedo reticularis may be a cutaneous manifestation of immune system disorders (e.g., lupus erythematosus, rheumatoid arthritis, cryoglobulinemia, lymphoma, etc), and hematologic disorders (polycythemia vera).

Patient EducationClinical

Immune System and Disorders

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

The full article covers:

  • What is the immune system?
  • What are the parts of the immune system?
  • How does the immune system work?
  • What are the types of immunity?
  • What can go wrong with the immune system?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert D84.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
279.3 Immunity deficiency NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D84.9Overview

What is the ICD-10 code for immunodeficiency, unspecified?

The ICD-10-CM code for immunodeficiency, unspecified is D84.9 (sometimes written as D849). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is D84.9 (Other immunodeficiencies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report immunodeficiency, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D84.9 group to?

When immunodeficiency, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 814, 815, 816, with relative weights from 0.6320 to 2.1267 depending on complications. Higher weights mean higher Medicare reimbursement.

Is D84.9 a CC or MCC?

CMS lists D84.9 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 44 closely related codes in its exclusion list.

What is the ICD-9 equivalent of D84.9?

Under the General Equivalence Mappings, immunodeficiency, unspecified converts to ICD-9-CM 279.3 (immunity deficiency NOS). The mapping is approximate, so confirm the match fits the documentation.

Does D84.9 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. D84.9 mapped to HCC 47 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 47 (Disorders of Immunity), ESRD (V21) category 47 (Disorders of Immunity), ESRD (V24) category 47 (Disorders of Immunity), and RxHCC Part D (V08) category 99 (Immune Disorders).