ICD-10-CM 2027
ICD-10 code for malignant mastocytoma
From the official ICD-10-CM alphabetic index entry “Mastocytoma (extracutaneous) › malignant”. Page updated September 29, 2026.
About coding malignant mastocytoma
The ICD-10-CM code for malignant mastocytoma is C96.29 (Other malignant mast cell neoplasm).
Within C96.2, choose C96.29 (Other malignant mast cell neoplasm) only when documentation doesn't support a more specific option: unspecified (C96.20), aggressive systemic mastocytosis (C96.21) and mast cell sarcoma (C96.22).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC, relative weight 5.6154), DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC, relative weight 4.381), DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC, relative weight 2.7307), DRG 820 (Lymphoma and Leukemia with Major O.R. Procedures with MCC, relative weight 6.2481), DRG 821 (Lymphoma and Leukemia with Major O.R. Procedures with CC, relative weight 2.2023), DRG 822 (Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC, relative weight 1.1272) and 6 more, in Pre-MDC and MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about malignant mastocytoma ICD-10 codes
What is the ICD-10 code for malignant mastocytoma?
- C96.29 — Other malignant mast cell neoplasm.
Is C96.29 billable?
- Yes. C96.29 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can C96.29 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict C96.29 as a principal diagnosis.
Is C96.29 a CC or MCC?
- C96.29 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.