What is ICD-10 code D84.0?

D84.0 is the ICD-10-CM diagnosis code for Lymphocyte function antigen-1 [LFA-1] defect. A rare immune system disorder where white blood cells lack a specific protein (LFA-1) needed to fight infections and communicate with other immune cells. D84.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D84.0 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. D84.0 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. D84.0 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for D84.0?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. D84.0 was a payment HCC under V24 (Disorders of Immunity) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D84.0?

This is a specific defect in cell adhesion molecules; document the specific immune function impairment if present May require additional codes for associated infections or complications Because D84.0 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM D84.0: Lymphocyte function antigen-1

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupD84.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Certain disorders involving the immune mechanism (D80-D89)

D84.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Lymphocyte function antigen-1 [LFA-1] defect

A rare immune system disorder where white blood cells lack a specific protein (LFA-1) needed to fight infections and communicate with other immune cells.

Buddy Insight

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Mapped

HCC 47

Disorders of Immunity

RAF 0.665

ACA/HHS

Mapped

HCC 74

HHS-HCC 74

Varies by metal level

ESRD/PACE

Mapped

HCC 47

Disorders of Immunity

RAF 0.078

RXHCC

Mapped

HCC 99

Immunodeficiencies

RAF 0.943

Code Book Path

Official

D84Other immunodeficiencies

D84.0Lymphocyte function antigen-1 [LFA-1] defect

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for D84.0 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for D84.0 in this effective period.

Related Child Codes

Official

D84.1Defects in the complement system

D84.8Other specified immunodeficiencies

D84.9Immunodeficiency, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for D84.0 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for D84.0 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D84.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for D84.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for D84.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must include flow cytometry demonstrating absent or reduced CD18/CD11a expression on leukocytes, persistent leukocytosis (white blood cell counts often exceeding 15,000 even without active infection), infection history with specific organisms, delayed cord separation history in infants, and genetic testing confirming ITGB2 gene mutation.

Document severity classification (severe with less than 2% expression vs.

moderate with 2-30%).

MEAT Support

HCC Buddy guidance

Document severity classification (severe with less than 2% expression vs.

moderate with 2-30%).

Audit Caution

HCC Buddy guidance

The hallmark of this condition is persistent leukocytosis without pus formation at infection sites due to the inability of neutrophils to migrate into tissues.

Do not confuse with neutropenia syndromes which have low white blood cell counts.

Delayed umbilical cord separation beyond 3 weeks is a key early clinical clue.

Code specific infections and wound complications separately.

Common Mistakes

HCC Buddy guidance

D84.89 (other immunodeficiencies when leukocyte adhesion deficiency is not specifically documented), D71 (functional disorders of polymorphonuclear neutrophils which may overlap clinically), D81.89 (other combined immunodeficiencies), D84.9 (immunodeficiency, unspecified).

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is D84.0 an HCC code?

Yes. D84.0 maps to Disorders of Immunity under the V24 model but is not retained in V28.

Code: D84.0
Description: Lymphocyte function antigen-1 [LFA-1] defect
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

V24HCC 47, Disorders of Immunity

0.665

ESRDHCC 47, Disorders of Immunity

0.078

RxHCCHCC 99, Immunodeficiencies

0.943

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work D84.0 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for D84.0

For D84.0 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D84.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

Get the V28 RAF + MEAT cheat sheet

One printable page: confirm a code's V28 HCC status, its RAF weight, and the MEAT your note needs to make it stick. Free, no card.

Free PDF. No card. Unsubscribe anytime.

What This Code Means

D84.0 is the ICD-10-CM diagnosis code for lymphocyte function antigen-1 [lfa-1] defect. A rare immune system disorder where white blood cells lack a specific protein (LFA-1) needed to fight infections and communicate with other immune cells. D84.0 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering certain disorders involving the immune mechanism (d80-d89).

Under the older CMS-HCC V24 model, D84.0 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.665. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

This is a specific defect in cell adhesion molecules; document the specific immune function impairment if present. Because D84.0 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D84.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a specific defect in cell adhesion molecules; document the specific immune function impairment if present
•May require additional codes for associated infections or complications

Clinical Significance

Lymphocyte function antigen-1 defect, also known as leukocyte adhesion deficiency type 1, is a rare autosomal recessive immunodeficiency caused by deficiency or dysfunction of the CD18 integrin subunit. This prevents neutrophils and other leukocytes from adhering to blood vessel walls and migrating to infection sites, resulting in severe recurrent bacterial and fungal infections with characteristically delayed umbilical cord separation and poor wound healing.

Documentation Requirements

✓Documentation must include flow cytometry demonstrating absent or reduced CD18/CD11a expression on leukocytes, persistent leukocytosis (white blood cell counts often exceeding 15,000 even without active infection), infection history with specific organisms, delayed cord separation history in infants, and genetic testing confirming ITGB2 gene mutation.
✓Document severity classification (severe with less than 2% expression vs.
✓moderate with 2-30%).

Commonly Confused Codes

•D84.89 (other immunodeficiencies when leukocyte adhesion deficiency is not specifically documented), D71 (functional disorders of polymorphonuclear neutrophils which may overlap clinically), D81.89 (other combined immunodeficiencies), D84.9 (immunodeficiency, unspecified).