ICD-10-CM 2027
ICD-10 code for mastocytosis
Other mast cell neoplasms of uncertain behavior
From the official ICD-10-CM alphabetic index entry “Mastocytosis”. Page updated September 29, 2026.
About coding mastocytosis
The ICD-10-CM code for mastocytosis is D47.09 (Other mast cell neoplasms of uncertain behavior). The official index lists 9 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on D47.09.
Within D47.0, choose D47.09 (Other mast cell neoplasms of uncertain behavior) only when documentation doesn't support a more specific option: cutaneous mastocytosis (D47.01) and systemic mastocytosis (D47.02).
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 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), DRG 823 (Lymphoma and Non-Acute Leukemia with Other Procedures with MCC, relative weight 4.6059), DRG 824 (Lymphoma and Non-Acute Leukemia with Other Procedures with CC, relative weight 2.2515), DRG 825 (Lymphoma and Non-Acute Leukemia with Other Procedures without CC/MCC, relative weight 1.2995) and 3 more, in 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.
More specific mastocytosis codes (official index)
- aggressive systemic C96.21 — Aggressive systemic mastocytosis
- cutaneous (diffuse) (maculopapular) D47.01 — Cutaneous mastocytosis
- congenital Q82.2 — Congenital cutaneous mastocytosis
- of neonatal onset Q82.2 — Congenital cutaneous mastocytosis
- of newborn onset Q82.2 — Congenital cutaneous mastocytosis
- indolent systemic D47.02 — Systemic mastocytosis
- isolated bone marrow D47.02 — Systemic mastocytosis
- malignant C96.29 — Other malignant mast cell neoplasm
- systemic (indolent) (smoldering)
- with an associated hematological non-mast cell lineage disease (SM-AHNMD) D47.02 — Systemic mastocytosis
Common questions about mastocytosis ICD-10 codes
What is the ICD-10 code for mastocytosis?
- D47.09 — Other mast cell neoplasms of uncertain behavior. More specific codes apply when the documentation supports them: C96.21, D47.01, Q82.2, Q82.2 and others below.
What is the ICD-10 code for aggressive systemic mastocytosis?
- C96.21 — Aggressive systemic mastocytosis.
What is the ICD-10 code for cutaneous mastocytosis?
- D47.01 — Cutaneous mastocytosis.
What is the ICD-10 code for indolent systemic mastocytosis?
- D47.02 — Systemic mastocytosis.
What is the ICD-10 code for isolated bone marrow mastocytosis?
- D47.02 — Systemic mastocytosis.
What is the ICD-10 code for malignant mastocytosis?
- C96.29 — Other malignant mast cell neoplasm.
Is D47.09 billable?
- Yes. D47.09 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can D47.09 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict D47.09 as a principal diagnosis.
Is D47.09 a CC or MCC?
- D47.09 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.