NPI Atlas

ICD-10 Code for Mastocytosis

The default ICD-10-CM 2027 code for mastocytosis is D47.09 – Other mast cell neoplasms of uncertain behavior. More specific codes depend on the details documented, as listed in the official index (6 codes, 6 billable).

Main code: D47.09 – Other mast cell neoplasms of uncertain behavior
Billable: Yes

Index entries for Mastocytosis

aggressive systemic – C96.21
cutaneous (diffuse) (maculopapular) – D47.01
- congenital – Q82.2
- of neonatal onset – Q82.2
- of newborn onset – Q82.2
indolent systemic – D47.02
isolated bone marrow – D47.02
malignant – C96.29
systemic (indolent) (smoldering)
- with an associated hematological non-mast cell lineage disease (SM-AHNMD) – D47.02

How to choose the right code

Start with the main term, then pick the indented subterm that matches the documentation (type, cause, site, laterality, episode of care). Always confirm the code in the tabular list: follow its Excludes1/Excludes2, “code first” and “use additional code” notes, and add a 7th character where required.

Source: CDC/NCHS ICD-10-CM FY2027 alphabetic index.