The April 1, 2026, ICD-10-CM diagnosis update introduces no new codes, deletions, or revisions. Instead, it represents a structural logic shift, altering sequencing rules and guidelines to give medical coders more reliance on clinical judgment.
Effective April 1, 2026, through September 30, 2026, the following updates are in place:
Excludes1 to Excludes2 Conversions: High-impact “Excludes1” notes were converted to “Excludes2,” allowing dual coding of distinct conditions in areas such as neoplasms, blood/immune disorders, respiratory failure, and long-term opiate use.
Instructional Note Changes: A major focus is the revision of “Excludes1” notes to “Excludes2” notes, particularly in Chapter 2 (Neoplasms). This shift allows for greater flexibility, as codes previously restricted (Excludes1) can now be reported together if clinically appropriate (Excludes2).
Key Areas (ICD-10-CM):
1. Category D49 Updates (Neoplasms of Unspecified Behavior)
Category D49 is utilized when a clinician notes a growth or mass but lacks the definitive pathology report to classify it as malignant or benign.
The Excludes1 note beneath D49 was replaced entirely with an Excludes2 note. This means you can now code D49 on the same claim layout alongside any of the following conditions:
- Arteriosclerotic Vascular Disease / Aneurysms: Permitting dual reporting with localized circulatory expansions or chronic blockages.
- Atheroma: Allowing simultaneous tracking of localized fatty skin deposits or sebaceous cysts alongside an undiagnosed mass.
- Congenital Anomalies of Neoplastic Sites: Coders can report an unspecified mass in an organ alongside a known congenital structural anomaly or birth defect of that same organ.
- Inflammation (Chronic or Acute): Resolves historical auditor conflict by allowing a code for active structural inflammation (e.g., chronic localized tissue inflammation) to be billed alongside an adjacent unspecified mass.
- Fat Necrosis: Traumatic or spontaneous fat necrosis masses can now be explicitly reported alongside an unrelated mass of unspecified behavior.
- Polyps: Specific localized polyps (which map to benign tissue classifications) can now be designated alongside a completely separate unspecified mass.
- Scar Tissue and Fibrosis: Deep structural scarring, keloids, or internal organ fibrosis can be captured simultaneously on the same encounter form as an unspecified lesion.
2. Category D18 Updates (Hemangioma and Lymphangioma, Any Site)
Category D18 captures benign vascular malformations and non-cancerous tumors composed of blood vessels or lymph vessels.
The Excludes1 note directly underneath category D18 was converted to an Excludes2 note. This change explicitly authorizes the dual reporting of hemangiomas/lymphangiomas
- Benign Neoplasm of Glomus Jugulare (6): Allows specialized neurological-vascular coding for skull base lesions
- Melanocytic Nevi (D22.-): Coders can report standard benign moles or congenital melanocytic distributions on the same claim as deep tissue hemangiomas.
Vascular Nevus (Q82.5): Structural, congenital birthmarks involving skin blood vessels (such as port-wine stains) are no longer blocked from being reported on a patient who also has a developing benign hemangioma tumor.
Coder Execution and Audit Strategy
Because these modifications went into effect for all medical claims on or after April 1, 2026, internal billing clearinghouses must adjust their automated screening mechanisms. To successfully dual-code these neoplasm combinations without trigger errors, verify the following item details
- Source Documentation: The clinical chart must show that the unspecified mass (D49) and the historical/inflammatory condition are anatomically distinct or clinically separate.
- Medical Necessity: Ensure that both conditions are evaluated, treated, or actively impact patient care within that specific encounter to satisfy standard coding guidelines.
Chapter 3: Diseases of the Blood & Blood-Forming Organs
- Category D72 (Other disorders of white blood cells): The Excludes1 note preventing concurrent tracking of neutropenia has been changed to an Excludes2
- Impact: Coders can now concurrently code D72 category conditions with codes from category D70 (Neutropenia).
Category B51 (Vitamin B12 deficiency anemia): The restrictive Excludes1 note barring code E53.8 (Vitamin B12 deficiency) was deleted. It was replaced with an Excludes2 note specifically for category E53 (Deficiency of other B group vitamins).
Chapter 6: Diseases of the Nervous System
- Code G35 (Multiple sclerosis) & Code G37.9 (Demyelinating disease of central nervous system, unspecified): The Excludes1 restriction between these codes has been completely eliminated and replaced with an Excludes2
Chapter 10: Diseases of the Respiratory System
- Subcategory J96.- (Respiratory failure, not elsewhere classified) & Code J95.82 (Postprocedural respiratory failure): This marks one of the highest financial-impact logic shifts of the April update
- Impact: The Excludes1 barrier was converted to an Excludes2 If a patient with pre-existing chronic or acute respiratory failure (J96.-) undergoes surgery and subsequently develops distinct postprocedural respiratory failure (J95.82), both codes are now reportable together. This significantly alters Complication or Comorbidity (CC/MCC) capture
Chapter 21: Factors Influencing Health Status (Z-Codes)
- Code Z79.891 (Long-term current use of opiate analgesics): The rigid Excludes1 block against methadone clinical classifications has been removed and replaced with an Excludes2
- Impact: Coders may now report Z79.891 alongside 9 (Methadone use, NOS) or F11.2 (Methadone use for treatment of heroin addiction) if a patient is undergoing dual management regimes.
Financial and MS-DRG Billing Implications for Respiratory Failure
The transition of the Excludes1 note to an Excludes2 note between category J96.- (Respiratory failure, not elsewhere classified) and code J95.82 (Postprocedural respiratory failure) represents a major revenue cycle shift.
- Dual Code Capture Allowed: Previously, you could not bill J96.- and J95.82 on the same claim layout due to the restrictive “not coded here” convention. You can now report both if they exist independently (e.g., a patient with pre-existing chronic respiratory failure undergoes surgery and develops acute postprocedural failure).
- CC/MCC Optimization: Chronic respiratory failure (J96.1-) is classified as a Complication or Comorbidity (CC), whereas acute postprocedural respiratory failure (J95.821) acts as a Major Complication or Comorbidity (MCC).
- DRG Upshifting: Successfully documenting and capturing both diagnoses will accurately shift claims into higher-weighted MS-DRGs, preventing underpayment for highly resource-intensive postoperative cases.
- POA Status Criticality: Clinical Documentation Integrity (CDI) teams must strictly validate the Present on Admission (POA) status. The underlying chronic respiratory failure must be flagged as POA “Y” (Yes), while the postprocedural acute failure must be flagged as POA “N” (No) to pass automated payer integrity audits.
Ophthalmology Sequencing Changes (H40.84)
The mid-year release fundamentally shifted code H40.84 (Neovascular secondary angle closure glaucoma) from a rigid “Code first” instruction to a flexible “Code also” instruction.
- Removal of Strict Sequencing Rules: Under the prior “Code first” mandate, coders were forced to sequence the underlying systemic or ocular etiology as the principal diagnosis, regardless of the clinical reason for the visit.
- Introduction of Coder Discretion: The “Code also” instructional note dictates no mandatory sequencing direction. The determination of the primary vs. secondary diagnosis is now dictated by the specific circumstances and documentation of the individual patient encounter.
Applicable Underlying Conditions: This sequencing logic directly applies when tracking H40.84 concurrently with conditions such as:
- Central retinal vein occlusion (H34.81)
- Diabetes mellitus with ophthalmic manifestations (E08.39, E10.39, E11.39)
- Retinal ischemia (H35.82)
- Audit and DRG Impacts: If an encounter is primarily focused on treating the acute secondary angle closure glaucoma, 84 can now legally occupy the principal diagnosis slot. This shifts the claim into an ophthalmology-focused DRG rather than an endocrine or systemic vascular DRG, significantly altering the expected reimbursement rate