MCMedicalCodingSoftware
D89.43

D89.43: Secondary mast cell activation

Billable / specific codeICD-10-CM

D89.43 is a billable, specific ICD-10-CM code for secondary mast cell activation. It is valid for submission on a claim.

Check D89.43 with the rest of the claim: free scrubber

Code also

Both codes may be needed to describe the encounter fully. Sequencing depends on the reason for the visit.

  • underlying etiology, if known

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

  • Secondary mast cell activation syndrome

Excludes1 inherited from the categories above D89.43

A category’s note binds every code beneath it.

Written on D89.4: Mast cell activation syndrome and related disorders

  • aggressive systemic mastocytosis (C96.21)
  • congenital cutaneous mastocytosis (Q82.2)
  • (non-congenital) cutaneous mastocytosis (D47.01)
  • (indolent) systemic mastocytosis (D47.02)
  • malignant mast cell neoplasm (C96.2-)
  • malignant mastocytoma (C96.29)
  • mast cell leukemia (C94.3-)
  • mast cell sarcoma (C96.22)
  • mastocytoma NOS (D47.09)
  • other mast cell neoplasms of uncertain behavior (D47.09)
  • systemic mastocytosis associated with a clonal hematologic non-mast cell lineage disease (SM-AHNMD) (D47.02)

Written on D89: Other disorders involving the immune mechanism, not elsewhere classified

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

Excludes2 inherited from the categories above D89.43

Not part of this code, but both may be coded when both are present.

Written on D89: Other disorders involving the immune mechanism, not elsewhere classified

  • transplant failure and rejection (T86.-)

Risk adjustment

No CMS-HCC V28 category: this code does not change a RAF score.

Medicare coverage

D89.43 is named in 11 Medicare coverage policies: 11 listing it as supporting medical necessity. Which one applies depends on your Medicare contractor.

  • A56638Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
  • A56642Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
  • A57689Billing and Coding: Lab: Flow Cytometry
  • A58575Billing and Coding: Respiratory Pathogen Panel Testing

Alphabetic index entries that lead here

  • Activation›mast cell›secondary

Code history

Unchanged in every release from FY2024 to FY2027.

Other codes under D89.4

ICD-10-CMFY2027· effective October 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release: see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.