ICD-10-CM › D50-D89 › D80-D89 › D89.4 Mast cell activation syndrome and... › D89.43

Valid for claims with a date of service in the current code year.

Valid FY2017 onwards.

What has happened to this code

Official coding rules

Published by CDC for FY2027. A rule attached to a category binds every code beneath it, so the rules inherited from this code's ancestors are shown with the code they come from.

Inherited from D89 Other disorders involving the immune mechanism, not elsewhere classified

Excludes1 - never coded here

• hyperglobulinemia NOS (R77.1)
• monoclonal gammopathy (of undetermined significance) (D47.2)

Excludes2 - not included here

• transplant failure and rejection (T86.-)

Inherited from the D80-D89 section Certain disorders involving the immune mechanism (D80-D89)

Excludes1 - never coded here

• autoimmune disease (systemic) NOS (M35.9)
• functional disorders of polymorphonuclear neutrophils (D71-)

Excludes2 - not included here

• human immunodeficiency virus [HIV] disease (B20)

Includes

• defects in the complement system
• immunodeficiency disorders, except human immunodeficiency virus [HIV] disease
• sarcoidosis

How CDC's index refers to this code

Wording from the official alphabetic index. Much of it appears nowhere in the code description, which is why a search for the everyday phrase so often finds nothing.

• Disorder > mast cell activation
• Syndrome > mast cell activation
• Activation > mast cell > secondary

Codes in the same group

Code	Description	Status
D89.40	Mast cell activation, unspecified	Valid
D89.41	Monoclonal mast cell activation syndrome	Valid
D89.42	Idiopathic mast cell activation syndrome	Valid
D89.44	Hereditary alpha tryptasemia	Valid
D89.49	Other mast cell activation disorder	Valid