D89.42
Billable
ChapterD50–D89
Ranksubcategory
Official Description
Idiopathic mast cell activation syndrome
Metadata & Insights
- •2026 ICD-10-CM Edition - Effective October 1, 2025.
- •Billable/specific code (valid for reimbursement).
- •Chapter 3: Diseases of the Blood and Blood-Forming Organs (D50-D89).
General instructions are available for the parent sections:
Clinical Hierarchy
CH3Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89)
D80-D89Certain disorders involving the immune mechanism (D80-D89)
D89Other disorders involving the immune mechanism, not elsewhere classified
D89.4Mast cell activation syndrome and related disorders
D89.42Idiopathic mast cell activation syndrome
Applicable Ancestor Context
The following parent sections contain instructions or notes that apply to D89.42:
categoryD89
Other disorders involving the immune mechanism, not elsewhere classified
View context instructionschapterCH3
Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89)
View context instructionsAlphabetic Index Mentions
These are Diagnosis Index lookup paths that route to D89.42. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.
1 raw paths
Activation1 unique routes
MS-DRG Classification
This code is grouped within the following Diagnosis Related Group(s) for clinical reimbursement:
Cross Reference
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