Search Database ICD-O-3 Code Lists

Name

Mast cell leukemia (MCL) (ICD-O-4: 97420/3)

ICD-O-3 Morphology

9742/3: Mast cell leukemia
Effective 2001 and later

Reportable

for cases diagnosed 1978 and later

Primary Site(s)

C421
Primary site must be bone marrow (C421)

Coding Manual: Hematopoietic Coding Manual (PDF)

Abstractor Notes

Mast cell leukemia (MCL) is part of the Mastocytosis lineage table in the WHO 5th edition of Hematolymphoid Tumors. (See Appendix B in the Hematopoietic Manual, Table B3)

If Mast cell sarcoma occurs at the same time or after Mast cell leukemia, this is one primary, the Mast cell leukemia (see M3 and Module 5:PH 9.)

The presence of Mast cell sarcoma after a diagnosis of Mast cell leukemia is progression of the Mast cell leukemia, not a new primary.

Diagnostic Confirmation

Assign code 1 for histological confirmation WITH or WITHOUT positive immunophenotyping or genetics

Module Rule

None

Alternate Names

None

Definition

Mast cell leukemia is the leukemic variant of systemic mastocytosis (9741/3) in which bone marrow aspirate smears contain greater than or equal to 20% mast cells. These mast cells are usually immature and atypical and are often round rather than spindle-shaped.

In classic mast cell leukemia, mast cells account for greater than or equal to 10% of the peripheral white blood cells.

In most patients, skin lesions are detectable. Bone marrow biopsy shows a diffuse, dense infiltration with atypical, immature mast cells. Organ damage is usually present at diagnosis.

Definitive Diagnostic Methods

Cytogenetics
Genetic testing
Histologic confirmation

Genetics Data

KIT mutations (excluding p.D816V)

Immunophenotyping

CD2, CD25, CD30, CD117, mast cell tryptase

Treatments

Chemotherapy

Transformations to

There are no known transformations

Transformations from

There are no known transformations

Same Primaries

Corresponding ICD-10 Codes (Cause of Death codes only)

C94.3 Mast cell leukemia

Corresponding ICD-10-CM Codes (U.S. only)

C94.3 Mast cell leukemia (effective October 01, 2015 - September 30, 2024)
C94.30 Mast cell leukemia not having achieved remission (effective October 01, 2024)
C94.31 Mast cell leukemia, in remission (effective October 01, 2024)
C94.32 Mast cell leukemia, in relapse (effective October 01, 2024)

Signs and Symptoms

Abdominal pain
Arthralgias
Bleeding (hemorrhage)
Bone pain
Dermatographism
Diaphoresis
Fatigue
Fever
Flushing
Fractures
Gastrointestinal distress
Headache
Hepatosplenomegaly
Hypotension
Myalgias
Neutropenia
Osteopenia/osteoporosis
Peptic ulcer
Pruritis
Respiratory problems
Syncope
Tachycardia
Thrombocytopenia
Urticaria
Weight loss

Diagnostic Exams

Bone marrow aspiration and biopsy
CT (CAT) scan
Cytogenetic analysis
Flow cytometry
Immunophenotyping
Molecular analysis
Peripheral blood smear
Physical exam and history
Skeletal survey
Skin biopsy

Progression and Transformation

None

Epidemiology and Mortality

Survival: ~ few months

Sources

WHO Classification of Tumours Editorial Board. Haematolymphoid tumours. Lyon (France): International Agency for Research on Cancer; 2024. (WHO classification of tumours series, 5th ed.; vol. 11). https://publications.iarc.who.int/637.
Section: Mastocytosis
Pages: Part A: 64-70

International Classification of Diseases for Oncology, 3rd edition (including revisions). Geneva: World Health Organization, 2001, 2011, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577
Glossary