D81.82
BillableActivated Phosphoinositide 3-kinase Delta Syndrome [APDS]
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D81.82 an HCC code?
Yes. D81.82 maps to Common Variable and Combined Immunodeficiencies under the CMS-HCC V28 risk adjustment model (and Disorders of Immunity under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for D81.82
For D81.82to 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 D81.82 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D81.82 is the ICD-10-CM diagnosis code for activated phosphoinositide 3-kinase delta syndrome [apds]. APDS is a rare genetic immune disorder where the body's immune system doesn't work properly due to a defect in a specific protein, making patients prone to recurrent infections and other immune complications. This condition is caused by mutations in genes that affect how immune cells communicate and function. D81.82 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 CMS-HCC V28 risk adjustment model, D81.82 maps to Common Variable and Combined Immunodeficiencies (HCC 114) with a community, non-dual, aged base RAF weight of 2.262. Under the older CMS-HCC V24 model, D81.82 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.
APDS is a rare disease that requires documentation of the specific genetic mutation (APDS1 or APDS2) when available, as this may affect treatment decisions and genetic counseling. Because D81.82 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 D81.82 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •APDS is a rare disease that requires documentation of the specific genetic mutation (APDS1 or APDS2) when available, as this may affect treatment decisions and genetic counseling
- •Ensure documentation includes any associated complications such as recurrent infections, lymphoproliferation, or autoimmune manifestations, as these should be coded separately to capture the full clinical picture
Clinical Significance
Activated Phosphoinositide 3-kinase Delta Syndrome is a recently characterized primary immunodeficiency caused by gain-of-function mutations in the PIK3CD (type 1) or loss-of-function mutations in PIK3R1 (type 2) genes. The condition causes immune dysregulation with recurrent sinopulmonary infections, lymphoproliferation, herpesvirus susceptibility, and increased risk of B-cell lymphoma, making it both an immunodeficiency and a lymphoproliferative predisposition syndrome.
Documentation Requirements
- ✓Documentation must include genetic testing confirming the specific mutation (PIK3CD or PIK3R1), clinical manifestations including lymphoproliferation (lymphadenopathy, hepatosplenomegaly), infection history with specific organisms, immunoglobulin levels, lymphocyte subset analysis, and treatment approach.
- ✓Document monitoring for lymphoma development and any targeted therapy (leniolisib or other PI3K delta inhibitors).
Code Also
Commonly Confused Codes
- •D81.89 (other combined immunodeficiencies, used before Activated Phosphoinositide 3-kinase Delta Syndrome had its own code), D83.0 (common variable immunodeficiency with B-cell abnormalities which can present similarly), D47.Z9 (other lymphoproliferative disorders when lymphoproliferation is the primary feature), D81.9 (combined immunodeficiency, unspecified).