How Is Systemic Mastocytosis Staged And Classified?

Systemic mastocytosis (SM) is a disorder characterized by an abnormal accumulation of mast cells in one or more organ system. The World Health Organization (WHO) has established a classification system for SM, which is based on the presence of specific criteria.

How is Systemic Mastocytosis Staged?

The staging of systemic mastocytosis is based on the extent of organ involvement and the presence of associated hematologic non-mast cell lineage disease (AHNMD). The stages include:

• Indolent systemic mastocytosis (ISM): This is the most common form of SM. Patients with ISM have symptoms related to mast cell mediator release and/or infiltration, but they do not have organ damage.
• Smoldering systemic mastocytosis (SSM): This is a more aggressive form of SM. Patients with SSM have a high burden of mast cells in their bone marrow and other organs, and they may have signs of organ damage.
• Systemic mastocytosis with an associated hematologic non-mast cell lineage disease (SM-AHNMD): In this form of SM, patients have another hematologic disorder in addition to SM.
• Aggressive systemic mastocytosis (ASM): This is a rare form of SM. Patients with ASM have organ damage caused by the infiltration of mast cells into various organ systems.
• Mast cell leukemia (MCL): This is the most aggressive form of SM. Patients with MCL have a very high burden of mast cells in their bone marrow and other organs, and they have severe organ damage.

Classification of Systemic Mastocytosis

The WHO classification of systemic mastocytosis includes the following categories:

• Indolent systemic mastocytosis (ISM)
• Smoldering systemic mastocytosis (SSM)
• Systemic mastocytosis with an associated hematologic non-mast cell lineage disease (SM-AHNMD)
• Aggressive systemic mastocytosis (ASM)
• Mast cell leukemia (MCL)
• Mast cell sarcoma (MCS)
• Extracutaneous mastocytoma

Phases of Systemic Mastocytosis

Systemic mastocytosis is a chronic disease that can progress over time. The phases of the disease are typically defined by the stage of the disease, with the early phase characterized by ISM, the intermediate phase by SSM and SM-AHNMD, and the late phase by ASM and MCL. The progression of the disease is usually slow, but it can be rapid in some cases, particularly in patients with ASM or MCL.

Want to Learn More About Systemic Mastocytosis?

Keep reading HealthTree for Systemic Mastocytosis's 101 pages!

• What Is Systemic Mastocytosis?
• How Is Systemic Mastocytosis Diagnosed?
• How Long Will I Live With Systemic Mastocytosis?
• What Are The Signs And Symptoms Of Systemic Mastocytosis?
• What Are Treatments For Systemic Mastocytosis?