2026 ICD-10-CM Diagnosis Code D47.09Other mast cell neoplasms of uncertain behavior

ICD-10-CM Codes›C00–D49›D37-D48›D47

ICD-10-CM D47.09
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D47.09 is a billable ICD-10-CM diagnosis code for other mast cell neoplasms of uncertain behavior. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 820 through 825, 840 through 842. Coders also document this condition as localized extracutaneous mastocytosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neoplasms of unspecified nature or uncertain behavior.

Code Identity

ICD-10-CM Code
D47.09
Billable Status
Yes — Valid for Submission
Code Describes
Other mast cell neoplasms of uncertain behavior
Short Description
Other mast cell neoplasms of uncertain behavior
Same as the full description in the CMS dataset.
Parent Code
D47.0
Mast cell neoplasms of uncertain behavior

Code Classification

ChapterC00–D49Neoplasms
SectionD37-D48Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes
CategoryD47Other neoplasms of uncertain behavior of lymphoid, hematopoietic and related tissue
This CodeD47.09Other mast cell neoplasms of uncertain behavior

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Localized extracutaneous mastocytosis
  • Mast cell disorder
  • Mast cell neoplasm
  • Mastocytoma
  • Systemic mast cell disease

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Extracutaneous mastocytoma
  • Mast cell tumor NOS
  • Mastocytoma NOS
  • Mastocytosis NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

  • - Tumor - See Also: Neoplasm, unspecified behavior, by site;

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Mast cell
      • neoplasm
        • of uncertain behavior NEC
    • Mast cell
      • tumor
    • Mastocytoma(extracutaneous)
    • Mastocytosis
    • Neoplasm, neoplastic
      • mast cell, of uncertain behavior NEC
    • Tumor
      • mast cell

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO072
Neoplasms of unspecified nature or uncertain behavior
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Mast-Cell Sarcoma

    a unifocal malignant tumor that consists of atypical pathological mast cells without systemic involvement. it causes local destructive growth in organs other than in skin or bone marrow.

  • Mastocytoma

    a solid tumor consisting of a dense infiltration of mast cells. it is generally benign.

  • Mastocytoma, Skin

    a variant of cutaneous mastocytosis which occurs as a single lesion usually in infants. it is found mostly in the wrist and trunk and there is no atypical cytomorphology.

  • Mast Cells

    granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. like the basophils, mast cells contain large amounts of histamine and heparin. unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor.

Convert D47.09 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
238.5 Mastocytoma NOS
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement D47.09 replaces the following previously assigned code(s):

  • D47.0 - Histiocytic and mast cell tumors of uncertain behavior
  • D47.0 - Mast cell neoplasms of uncertain behavior
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D47.09Overview

Is D47.09 (Mast cell neoplasms of uncertain behavior) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other mast cell neoplasms of uncertain behavior on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D47.09 group to?

When other mast cell neoplasms of uncertain behavior is the principal diagnosis on an inpatient stay, it groups to MS-DRG 820, 821, 822, 823, 824, 825, 840, 841, 842, with relative weights from 1.0104 to 5.8648 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of D47.09?

Under the General Equivalence Mappings, other mast cell neoplasms of uncertain behavior converts to ICD-9-CM 238.5 (mastocytoma NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.