ICD-10 Codes

The Mast Cell Disease Society has a strong background in collaboration to ensure the development of medical codes for mast cell disease. Coding for mastocytosis, MCAS and other newly identified mast cell diseases may require some revision, or even new coding proposals in the future, but overall, we now have very workable codes. These codes facilitate patients getting insurance coverage, applying for disability, and obtaining the medications they need. They also enhance recognition of these diseases and increase their credibility. Below is a summary of the ICD-10 CM Codes. If a code has a statement that it is non-billable, that means one has to select one of the more specific codes listed below the main code for billing purposes. NOS = “Not Otherwise specified”.

ICD-10-CM Diagnosis Codes (U.S.) 
Mastocytosis (2017/2018)
Q82.2 Congenital cutaneous mastocytosis

2016; 2017; 2018 – Revised Code; Billable/Specific Code; POA Exempt

  • Q82.2 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM Q82.2 is a revised 2018 ICD-10-CM code that becomes effective on October 1, 2017.
  • This is the American ICD-10-CM version of Q82.2 – other international versions of ICD-10 Q82.2 may differ.

Applicable To

  • Congenital diffuse cutaneous mastocytosis
  • Congenital maculopapular cutaneous mastocytosis
  • Congenital urticaria pigmentosa

Type 1 Excludes

  • cutaneous mastocytosis NOS (D47.01)
  • diffuse cutaneous mastocytosis (with onset after newborn period) (D47.01)
  • malignant mastocytosis (C96.2-)
  • systemic mastocytosis (D47.02)
D47.0 Mast cell neoplasms of uncertain behavior

2016; 2017; 2018 – Deleted Code; 2018 – New Code; Non-Billable/Non-Specific Code

  • D47.0 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail. (SEE below)
  • ICD-10-CM D47.0 is a new 2018 ICD-10-CM code that became effective on October 1, 2017.
  • This is the American ICD-10-CM version of D47.0 – other international versions of ICD-10 D47.0 may differ.

Type 1 Excludes

  • congenital cutaneous mastocytosis (Q82.2-)
  • histiocytic neoplasms of uncertain behavior (D47.Z9)
  • malignant mast cell neoplasm (C96.2-)
D47.01 Cutaneous mastocytosis

2018 – New Code; Billable/Specific Code

  • D47.01 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM D47.01 is a new 2018 ICD-10-CM code that becomes effective on October 1, 2017.
  • This is the American ICD-10-CM version of D47.01 – other international versions of ICD-10 D47.01 may differ.

Applicable To

  • Diffuse cutaneous mastocytosis
  • Maculopapular cutaneous mastocytosis
  • Solitary mastocytoma
  • Telangiectasia macularis eruptiva perstans
  • Urticaria pigmentosa

Type 1 Excludes

  • congenital (diffuse) (maculopapular) cutaneous mastocytosis (Q82.2)
  • congenital urticaria pigmentosa (Q82.2)
  • extracutaneous mastocytoma (D47.09)
D47.02 Systemic mastocytosis

2018 – New Code; Billable/Specific Code

  • D47.02 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM D47.02 is a new 2018 ICD-10-CM code that becomes effective on October 1, 2017.
  • This is the American ICD-10-CM version of D47.02 – other international versions of ICD-10 D47.02 may differ.

Applicable To

  • Indolent systemic mastocytosis
  • Isolated bone marrow mastocytosis
  • Smoldering systemic mastocytosis
  • Systemic mastocytosis, with an associated hematological non-mast cell lineage disease (SM-AHNMD)
D47.09 Other mast cell neoplasms of uncertain behavior

2018 – New Code; Billable/Specific Code

  • D47.09 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM D47.09 is a new 2018 ICD-10-CM code that became effective on October 1, 2017.
  • This is the American ICD-10-CM version of D47.09 – other international versions of ICD-10 D47.09 may differ.

Applicable To

  • Extracutaneous mastocytoma
  • Mast cell tumor NOS
  • Mastocytoma NOS
  • Mastocytosis NOS
C96.2 Malignant mast cell neoplasm

2016; 2017; 2018 – Deleted Code; 2018 – New Code; Non-Billable/Non-Specific Code

  • C96.2 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail. (SEE below)
  • ICD-10-CM C96.2 is a new 2018 ICD-10-CM code that became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C96.2 – other international versions of ICD-10 C96.2 may differ.
C96.21 Aggressive systemic mastocytosis

2018 – New Code; Billable/Specific Code

  • C96.21 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM C96.21 is a new 2018 ICD-10-CM code that becomes effective on October 1, 2017.
  • This is the American ICD-10-CM version of C96.21 – other international versions of ICD-10 C96.21 may differ.
C96.22 Mast cell sarcoma

2018 – New Code; Billable/Specific Code

  • C96.22 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM C96.22 is a new 2018 ICD-10-CM code that becomes effective on October 1, 2017.
  • This is the American ICD-10-CM version of C96.22 – other international versions of ICD-10 C96.22 may differ.
C96.20 Malignant mast cell neoplasm, unspecified

2018 – New Code; Billable/Specific Code

  • C96.20 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM C96.20 is a new 2018 ICD-10-CM code that became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C96.20 – other international versions of ICD-10 C96.20 may differ.
C96.29 Other malignant mast cell neoplasm

2018 – New Code; Billable/Specific Code

  • C96.29 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • ICD-10-CM C96.29 is a new 2018 ICD-10-CM code that became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C96.29 – other international versions of ICD-10 C96.29 may differ.
C94.3 Mast cell leukemia

2016; 2017; 2018; Non-Billable/Non-Specific Code

  • C94.3 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail. (SEE below)
  • The 2018 edition of ICD-10-CM C94.3 became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C94.3 – other international versions of ICD-10 C94.3 may differ.
C94.31 Mast cell leukemia, in remission

2016; 2017; 2018; Billable/Specific Code

  • C94.31 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2018 edition of ICD-10-CM C94.31 became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C94.31 – other international versions of ICD-10 C94.31 may differ
C94.32 Mast cell leukemia, in relapse

2016; 2017; 2018; Billable/Specific Code

  • C94.32 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2018 edition of ICD-10-CM C94.32 became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C94.32 – other international versions of ICD-10 C94.32 may differ.
C94.30 Mast cell leukemia, not having achieved remission

2016; 2017; 2018; Billable/Specific Code

  • C94.30 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2018 edition of ICD-10-CM C94.30 became effective on October 1, 2017.
  • This is the American ICD-10-CM version of C94.30 – other international versions of ICD-10 C94.30 may differ.

Applicable To

  • Mast cell leukemia with failed remission
  • Mast cell leukemia NOS
Mast Cell Activation Syndrome (2017/2018)
D89.4 Mast cell activation syndrome and related disorders

2017 – New Code; 2018; Non-Billable/Non-Specific Code

  • D89.4 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail. (SEE below)
  • The 2018 edition of ICD-10-CM D89.4 became effective on October 1, 2017.
  • This is the American ICD-10-CM version of D89.4 – other international versions of ICD-10 D89.4 may differ.
  • 40 Mast cell activation, unspecified
  • 41 Monoclonal mast cell activation syndrome
  • 42 Idiopathic mast cell activation syndrome
  • 43 Secondary mast cell activation
  • 49 Other mast cell activation disorder

Type 1 Excludes

  • aggressive systemic mastocytosis (C96.21)
  • congenital cutaneous mastocytosis (Q82.2)
  • (non-congenital) cutaneous mastocytosis (D47.01)
  • (indolent) systemic mastocytosis (D47.02)
  • malignant mast cell neoplasm (C96.2-)
  • malignant mastocytoma (C96.29)
  • mast cell leukemia (C94.3-)
  • mast cell sarcoma (C96.22)
  • mastocytoma NOS (D47.09)
  • other mast cell neoplasms of uncertain behavior (D47.09)
  • systemic mastocytosis associated with a clonal hematologic non-mast cell lineage disease (SM-AHNMD) (D47.02)
Hereditary alpha tryptasemia (2021)
D89.44 Hereditary alpha tryptasemia

The CDC has released an ICD-10 code for HaT. This achievement will enhance recognition of HaT and acknowledge the advancements being made in this newly identified gene duplicate. We look forward to better patient data for our understanding, and most importantly insurance coverage and overall improved patient care.

View all References
  1. Valent P, Akin C, Arock M, Brockow K, Butterfield JH, Carter MC, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol. 2012;157(3):215-25.
  2. Lyons JJ, Yu X, Hughes JD, Le QT, Jamil A, Bai Y, et al. Elevated basal serum tryptase identifies a multisystem disorder associated with increased TPSAB1 copy number. Nat Genet. 2016 Dec;48(12):1564-9.
  3. https://www.cdc.gov/nchs/icd/icd10cm.htm

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