dense infiltration

73. Can mast cell disease cause organ damage?

• Yes.
• The term organ damage is tricky because people use it to mean a lot of things while providers and researchers often use it to mean one very specific thing. For providers and researchers, the term “organ damage” usually means a change in the organ that affects its structure, like it becomes misshapen or deformed in some way. Structural changes like this are often irreversible. This damage to the organ’s shape and structure usually affects how the organ works, called organ function.
• When patients and laypeople talk about organ damage, they usually mean a change in the way the organ functions, even if the structure is not changed at all. This is different in a very important way: changes in an organ that do not affect its permanent structure can sometimes be reversible.
• Both cutaneous and systemic mastocytosis cause organ damage in a way that damages the organ’s structure. When too many mast cells burrow into the tissue of an organ, it has to push other things out of the way. When you have mastocytosis, the mast cells like to stick together and form a big clump in the tissue. This punches holes in the tissue, affecting the organ’s structure and shape. This is called dense infiltration. It is one of the criteria for systemic mastocytosis and also happens in cutaneous mastocytosis.
• In patients with mastocytosis, those mast cells clumping together cause a lot of the organ damage. This means that people who have the most mast cells usually have the worst organ damage. Patients with malignant forms of mast cell disease, like mast cell leukemia or aggressive systemic mastocytosis, often have organs that are riddled with TONS of mast cells.
• Mast cells don’t live in the blood so when your body makes way too many mast cells, those mast cells will dive into whatever organ they can to get out of the bloodstream. This causes damage to the structure that you can see with scans or in biopsies.  People with mast cell leukemia and aggressive systemic mastocytosis suffer so much damage to the shape and function of their organs that the organs can totally stop working, called organ failure.
• One of the key differences researchers and providers see between mastocytosis and mast cell activation syndrome is that mast cells don’t cause THIS TYPE of structural damage in mast cell activation syndrome patients.
• We know this because in biopsies, they do not have mast cells clumped together to punch holes in the tissue. Sometimes they have lots of mast cells, but it is much less damaging to the tissue if they aren’t clumped together. Think of it like poking something with finger versus punching with your fist.
• In MCAS, mast cells do not cause structural damage to organs IN THIS WAY. However, many people with MCAS do have structural damage to their organs. Many of them also have organs that do not function correctly even if the organs look normal.
• Even if you don’t have mast cells punching holes in all your organs, they can still do a lot of damage. This is because mast cells cause lots of inflammation, which can stress out your organs. Over time, your organs can be damaged by the mast cells releasing too many mediators. While this is not always dangerous, it is certainly painful and frustrating.
• Many MCAS and mastocytosis patients have a lot of damage to their GI tracts from years of vomiting, obstructions, diarrhea or constipation. Hives and mastocytosis spots can damage your skin, causing discoloration, scarring or sensitivity. Muscles can become weaker over time because of mast cell inflammation. Swelling can stretch out your skin and connective tissues. Nerves can be damaged significantly, affecting organ function. Bones can become brittle and break, or can become too dense because the body is making new bone when it shouldn’t.
• All of these effects on organ function can be caused by mast cells. Major changes in organ function can also cause secondary conditions to arise.
• Mast cell patients are also at an increased risk for anaphylaxis which can cause changes in organ function or organ damage.
• Patients who have trouble breathing or low blood pressure may not be getting enough oxygen to their whole body. That can cause lasting damage if it goes on long enough.

For more detailed reading, please visit the following posts:

• Cutaneous mastocytosis/Mastocytosis in the skin
• Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)
• Introduction to Mast Cells
• Management of mast cell mediator symptoms and release
• Mast cell activation syndrome (MCAS)
• Natural history of SM-AHD, MCL and MCS