ICD-9-CM diagnosis code (retired)
279.8 — Other specified disorders involving the immune mechanism
ICD-9-CM was replaced by ICD-10 on October 1, 2015. These are the ICD-10-CM equivalents from the CMS General Equivalence Mappings.
About ICD-9-CM 279.8
279.8 is an ICD-9-CM diagnosis code for other specified disorders involving the immune mechanism. ICD-9-CM was retired for U.S. claims on October 1, 2015, when ICD-10-CM took over.
The CMS General Equivalence Mappings translate it to 8 ICD-10-CM codes, such as D84.1 (Defects in the complement system), D89.40 (Mast cell activation, unspecified) and D89.41 (Monoclonal mast cell activation syndrome). All of these are approximate matches, so review the record to pick the right one.
ICD-10-CM equivalents
- D84.1Defects in the complement systemapproximate
- D89.40Mast cell activation, unspecifiedapproximate
- D89.41Monoclonal mast cell activation syndromeapproximate
- D89.42Idiopathic mast cell activation syndromeapproximate
- D89.43Secondary mast cell activationapproximate
- D89.49Other mast cell activation disorderapproximate
- D89.89Other specified disorders involving the immune mechanism, not elsewhere classifiedapproximate
- M35.9Systemic involvement of connective tissue, unspecifiedapproximate
Common questions about 279.8
GEMs are a translation aid, not a substitute for coding from the record. The 2027 ICD-10 code set has changed since the last GEMs release in 2018. Page updated September 29, 2026.