D71 vs D89.42
D71 (Functional disorders of polymorphonuclear neutrophils) compared with D89.42 (Idiopathic mast cell activation syndrome), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. D89.42 carries an Excludes1 note covering D71: “functional disorders of polymorphonuclear neutrophils (D71-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| D71Functional disorders of polymorphonuclear neutrophils | D89.42Idiopathic mast cell activation syndrome | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | D50-D89 — Diseases of the Blood and Blood-forming Organs and Certain Disorders Involving the Immune Mechanism (D50-D89) | D50-D89 — Diseases of the Blood and Blood-forming Organs and Certain Disorders Involving the Immune Mechanism (D50-D89) |
| Definition | Functional disorders of polymorphonuclear neutrophils is a non-billable ICD-10-CM category code (D71). | Idiopathic mast cell activation syndrome is a billable ICD-10-CM diagnosis code (D89.42). |
| Includes | — | defects in the complement system immunodeficiency disorders, except human immunodeficiency virus [HIV] disease sarcoidosis |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources