ICD-10 Code D47.09 – Other mast cell neoplasms of uncertain behavior (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D47.09 – Other mast cell neoplasms of uncertain behavior
What it is
D47.09 identifies a mast cell neoplasm that is not otherwise specified and is classified as having uncertain behavior. Use it when the record documents a mast cell tumor or proliferation, but the exact malignant potential is not clearly established.
Clinical signs
Clinical features vary; refer to documentation. Records may describe mast cell involvement, abnormal mast cell proliferation, or a suspected mast cell neoplasm without enough detail to confirm a more specific category.
When to use this code
Use this code when the provider documents an “other” mast cell neoplasm and states uncertain behavior, or when the chart supports a mast cell neoplasm but does not specify a more exact diagnosis. It is appropriate when the documentation does not meet criteria for a clearly benign or malignant code. Check documentation if the pathology wording is limited or ambiguous.
Do not use for
Do not use D47.09 for clearly benign mast cell lesions or for confirmed malignant neoplasms with a more specific code. If the record names a different mast cell disorder or the behavior is stated differently, code that documented condition instead.
Coding tip
Code from the pathology or provider impression, and query when the behavior of the mast cell neoplasm is not clearly stated.