D89.4

Mast cell activation syndrome and related disorders

Diagnosis reference

Nonbillable category

This entry is a category or subcategory. Choose the appropriate billable descendant based on the clinical documentation.

Effective periodOctober 1, 2026–September 30, 2027

SourceCMS ICD-10-CM order file

ClassificationDiagnosis · clinical modification

Related entries

Up to 30 descendants in this category

CODE	DESCRIPTION	TYPE
D89.40	Mast cell activation, unspecified	Billable
D89.41	Monoclonal mast cell activation syndrome	Billable
D89.42	Idiopathic mast cell activation syndrome	Billable
D89.43	Secondary mast cell activation	Billable
D89.44	Hereditary alpha tryptasemia	Billable
D89.49	Other mast cell activation disorder	Billable

Use the complete reference

This reference does not reproduce the full tabular hierarchy, inclusion notes, Excludes1/2 notes, sequencing instructions, or seventh-character rules. Review the official tables and coding guidelines.

Open official CMS files

ICD-10-CM codes describe diagnoses. They do not have an independent Medicare PFS reimbursement amount, and billability alone does not establish coverage.