There are two main forms of mastocytosis: systemic mastocytosis (SM) and cutaneous mastocytosis. While the two forms of the disease share many similarities, they also have significant differences.
What is cutaneous mastocytosis?
Cutaneous mastocytosis primarily affects the skin, and most often occurs in children.
Like SM, cutaneous mastocytosis is the result of a KIT gene mutation. While in SM this mutation leads to mast cells accumulating in many areas of the body, in cutaneous mastocytosis they mainly accumulate in the skin.
As in SM, when these mast cells are activated they release histamines and other chemicals into the bloodstream that trigger an allergic reaction — but unlike in SM, in cutaneous mastocytosis this mainly effects just the skin.
There is no cure for cutaneous mastocytosis. Treatment focuses on relieving symptoms; antihistamines to ease itching are often prescribed. Cutaneous mastocytosis carries less of a disease burden than SM, and it often improves or resolves in puberty. However, in rare cases, children who have had cutaneous mastocytosis have been reported to develop SM later in life.
How do the symptoms of cutaneous mastocytosis compare with SM?
Cutaneous mastocytosis and SM are activated by many of the same symptom triggers, namely:
- Insect stings.
- Certain medications.
- Certain foods.
- Emotional stress.
- Physical exertion.
- Alcohol.
- Sudden changes in temperature.
- Pollen.
In cutaneous mastocytosis, these mainly trigger symptoms in the skin, such as:
- Itchiness, inflammation and flushing of the skin.
- Rashes, hives, and blistering of the skin.
However, in some cases of cutaneous mastocytosis, gastrointestinal symptoms may also occur, such as:
- Stomach pain.
- Diarrhea.
- Nausea.
In SM, on the other hand, symptoms are much more diverse, ranging from itchiness to anemia and bone pain.
Read more about SM signs and symptoms
People living with mastocytosis, regardless of the type, are at risk of developing life-threatening anaphylaxis and should carry two doses of epinephrine at all times.
Diagnosis of cutaneous versus systemic mastocytosis
Two-thirds of cutaneous mastocytosis cases develop during childhood. It is most often diagnosed in infants and toddlers: about half of children will have skin lesions by the time they are six months old. In comparison, SM is most often diagnosed in adults over the age of 50.
Cutaneous mastocytosis is diagnosed with a physical examination and then a skin biopsy to test for mast cells.
SM requires more in-depth testing, such as blood tests, ultrasounds, bone density scans and bone marrow biopsies.
Adults with cutaneous mastocytosis typically need more extensive testing than children, in order to rule out the possibility that they may have SM.
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