Understanding the Disease

Three Types of Systemic Mastocytosis (SM)

What are the Three Types of Systemic Mastocytosis?

There are three types of systemic mastocytosis. They are collectively referred to as advanced SM. They are:

  • Aggressive systemic mastocytosis (ASM)
  • Systemic mastocytosis with associated hematological neoplasm (SM-AHN) or
  • Mast cell leukemia (MCL)

SM is a condition that causes the body to produce too many mast cells. A mast cell, or mastocyte, is a type of white blood cell that helps your immune system and aids in wound healing. Mast cells work by releasing histamines, which can sometimes cause itching, sneezing, or swelling.

What does it mean when SM is advanced?

Advanced SM occurs when these mast cells grow out of control. The mast cells can travel through your body and enter your organs, where they may release histamines. This causes many of the same symptoms as an allergic reaction, which can make the condition hard to diagnose.


About 30% to 40% of all SM cases are advanced. Advanced SM refers to 3 types of SM.


Types of Advanced SM

types of advanced systemic mastocytosis
types of advanced systemic mastocytosis
types of advanced systemic mastocytosis

The type of SM you have will be diagnosed by your doctor. It is important to find out if your SM is advanced, as it will determine how the disease is treated.