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mast cell activation syndrome

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 38

45. Is mast cell disease autoimmune?

An autoimmune disease is the result of a patient’s immune system specifically targeting a normal, healthy part of their body. How particularly and precisely the immune system identifies part of the body to attack is very important to understanding my answer to this question.

Let’s look at some autoimmune diseases as examples.

Autoimmune thyroiditis (also called Hashimoto’s thyroiditis) is a prevalent autoimmune disease that targets the thyroid. The thyroid’s job is to make hormones that tell your body to do other things. These hormones are called thyroid hormones. When you have autoimmune thyroiditis, your immune system makes antibodies that target the thyroid and thyroid hormones. These are called autoantibodies. They target a normal part of body. There is no reason for the body to make these autoantibodies. They do not perform any healthy function for the body. The only function they serve is to attack part of the body.

When you have autoimmune thyroiditis, the immune system makes antibodies to things that are only found in the thyroid or made by the thyroid. (I’m being very general here.) Other autoimmune diseases target parts of the body that are found throughout the body so that the effects of the disease are more widespread. However, those diseases still target specific things.

Lupus is an autoimmune disease that affects many places in the body by precisely attacking things found throughout the body. The cells in your body all have DNA inside of them. This DNA has the genes to make proteins and other things your body needs. If the cell can’t use the DNA inside it correctly, it makes your body sick. This is exactly what happens in lupus. Lupus makes autoantibodies and attacks things inside your cells that your body needs to use the DNA. Because all of the cells in your body need to use their DNA, the things lupus attacks are found all over the body, not just one organ. But even though lupus attacks many organs and places throughout your body, it is still targeted to harm specific pieces of the body.

In autoimmune disease, the body makes specific things for the explicit purpose of damaging specific things.

Now let’s talk about mast cell disease.

Currently, mast cell diseases are not considered to be autoimmune by most – but not all – experts. (I’ll circle back to this.) When a person has mast cell disease, the fundamental issue is that they release tons of mast cell mediators at times when they shouldn’t, causing symptoms and damage to the body. But even though those chemicals can cause all kinds of problems, they are not targeted to attack specific structures. This is where the distinction is from autoimmune diseases. Mast cells release tons of histamine, but that histamine isn’t targeted to find a specific molecule inside of a liver cell. They release prostaglandin D2, but that PGD2 isn’t made for the particular purpose of attacking one particular thing inside of your thyroid.

Instead, the molecules released incorrectly by mast cells affect whatever cells are in its path. This is one of the reasons why there is such variability in symptoms and disease effects for mast cell patients. What parts of the body are affected the most is dependent upon a million things happening in the patient’s body. This is because the chemicals mast cells release are not targeted to any one place. They are just released by the mast cell and they go wherever they can before the body breaks them down.

I mentioned above that most experts did not consider mast cell diseases to be autoimmune, but not all of them. So let’s go back to that. Mastocytosis is not considered autoimmune but anyone as far as I am aware. There is absolutely no evidence that mastocytosis is autoimmune after decades of research. But MCAS is a newer entity and so there is less information on it due to less time spent researching it. There are still a lot of questions around MCAS and some experts think that whether or not it is autoimmune is one of them.

We know that at the very least that there is a connection between MCAS and autoimmune disease. Many MCAS patients have autoimmune disease, often more than one. We think MCAS occurs secondarily to the autoimmune disease in these patients. There’s also the fact that many MCAS patients are positive for ANA (antinuclear antibody), an autoantibody linked to lupus, even though they don’t have a diagnosed autoimmune disease that would cause that to be positive. Some people think that maybe MCAS is the autoimmune disease in that situation and that ANA is a marker indicating that MCAS is autoimmune. I have mentioned elsewhere that while we consider MCAS to usually be a secondary disease, there are some patients for whom we can’t find a primary disease. It is possible that MCAS is a primary condition in those people and that it is autoimmune.

You still need to keep in mind that even if we say that maybe the positive ANA shows that MCAS is autoimmune, there is still no evidence of any kind that indicates that mast cell mediators target a specific part of the body – a defining characteristic of autoimmune disease. That doesn’t mean there isn’t an autoantibody or some other mechanism for targeting precise structures in the body, just that we have no evidence of one existing right now.

Let’s recap: currently, most experts believe that mast cell diseases are not autoimmune because they do not target specific normal, healthy structures in the body. Mastocytosis is roundly agreed to not be autoimmune. There are some experts who feel that at least some cases of MCAS might be autoimmune. They feel this way because of the clear link between MCAS and other autoimmune diseases, as well as the fact that many MCAS patients are positive for an autoimmune marker, ANA, without evidence of an autoimmune disease that would explain that.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 34

41. Can my mast cell disease go away? Will it ever not be a problem?

There are several common questions that basically all distill down to these sentiments. I’m going to answer them all here.

I have previously answered the question “Can mast cell disease be cured?” in this series but I think this question is a little different. When people ask if mast cell disease can go away, they mean can it become no longer a problem even if it’s not cured. That’s what I’m answering here.

This answer is very complicated so I’m just going to give my thoughts let’s about all sides of this situation.

Yes, it is possible for mast cell disease to be controlled enough to no longer be a problem in your life. But there are a lot of caveats.

The most common presentation of mast cell disease in cutaneous mastocytosis (mastocytosis in the skin) in children. In about 2/3 of cases, children “grow out of” their mast cell disease. Specifically, this means that they lose their skin lesions and have no obvious mast cell symptoms by their late teenage/early adult years. We don’t know why this happens.

However, there are instances where a person who grew out of their childhood CM have mast cell issues later in life. We have a greater understanding of mast cell diseases now and we know that you can have a whole host of mast cell issues without having skin lesions. So it’s not as clean cut as was previously thought.

For more serious forms of systemic mastocytosis, it is possible that with treatment, the disease can be “knocked down” to a less serious category. For example, a patient with aggressive systemic mastocytosis who does chemo may find that it helped enough that their diagnosis is now smoldering systemic mastocytosis. Or a patient with SSM has a big drop in the number of mast cells zooming around after taking interferon and now they have indolent systemic mastocytosis. While symptom severity doesn’t necessarily change when a patient has a less serious diagnosis, that does sometimes happen.

With the exception of childhood cutaneous mastocytosis, all other forms of mastocytosis are considered lifelong ventures. This includes all forms of adult onset cutaneous mastocytosis and all forms of systemic mastocytosis for children or adults. However, there are instances of patients with SM where bone marrow transplant seems to cure their disease. We need to continue to follow mast cell patients who have had bone marrow transplants to see how many of them have recurrence of mast cell disease.

Mast cell activation syndrome is often secondary to some other condition. Basically, one disease irritates your body so much that your mast cells flip out in response to the disease. The disease that caused the mast cell problem is called the primary condition. In these instances, mast cell activation syndrome is sometimes considered to be dependent upon the primary condition. This means that some doctors and researchers feel that if you control the primary condition, the mast cell activation syndrome will go away.

This sentiment seems straightforward but is actually pretty complex. Let’s pull it apart. Let’s say your primary condition is lupus. You are a patient with lupus. The lupus irritates your body so much that your mast cells just go bananas. Now you are a patient with lupus who has secondary MCAS. The lupus in this instance caused the MCAS. But what does that mean? Does that mean that without the lupus, you would never have had MCAS? Or does it mean that you would eventually have had MCAS secondary to something else? This is the topic of a lot of debate. (I personally am of the belief that MCAS is genetic and therefore you were always going to develop it at some point.) So it’s not clear yet whether a primary condition really “causes” MCAS or just wakes it up.

However, what is not disputed at all is that any type of inflammation can trigger mast cell activation and symptoms. So if you are a lupus patient, and your lupus is going crazy, that’s going to really bug your mast cells. If you are able to control your lupus, it will decrease the inflammation, which will calm your mast cells. But calming your mast cells isn’t really the same thing as your mast cell disease going away. Not having symptoms is not the same thing as being cured.

Another thing to consider is that even if the lupus is what triggered your MCAS, once your MCAS is triggered, it’s going to be triggered by everything. You can very easy get locked into a cycle where the lupus irritates your MCAS, which irritates your lupus, and around you go. So in a situation like this, where the mast cell activation is really out of control, it sometimes doesn’t matter what the primary condition is, and controlling the primary condition might not help.

Many patients with mast cell disease have their symptoms controlled enough to live pretty normal lives. Some mast cell patients don’t have really symptoms at all, even without medications. In a small group of MCAS patients, after a year of treatment with antihistamines and mast cell stabilizers, about 1/3 had complete resolution of symptoms and another 1/3 had one only symptom that was a problem. 

However, it’s important to remember that this is not having debilitating symptoms is not the same as not having mast cell disease. These patients are still predisposed towards mast cell activation and should take mast cell precautions for things like surgery or dental work. Many patients stay on antihistamines and/or a mast cell stabilizer even with good symptom control because it affords some protection from bad reactions and anaphylaxis. Patients should only stop regular medication with the supervision and direction of a provider who knows them. Additionally, trialing things like foods you reacted to, or starting an exercise program, require provider input.

You should also keep in mind that mast cell disease can be very erratic. It doesn’t always follow a trend so symptoms steadily improving does not guarantee that symptoms will stay well controlled. So while mast cell disease can be managed enough to not be a problem, there is always the possibility that it will show up again. Once you have a mast cell diagnosis, you are always going to be looking over your shoulder.

 

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 33

40. What is mastocytosis of childhood? Is mast cell disease different for children than adults?

Cutaneous mastocytosis in children is the most common form of mastocytosis. True systemic mastocytosis, in which the WHO criteria are met, is very rare in children.

In many ways, mastocytosis in children has huge differences from mastocytosis in adults. The exact reason for this is unclear. Because of how different the disease path can be for children, doctors and researchers sometimes refer it as mastocytosis of childhood. However, there is not officially a distinct diagnostic category.

Unlike in adults, mastocytosis in children is sometimes both benign and transient. Many kids have symptoms that either stay the same or improve as they get older. Many kids grow out of their mastocytosis. About 2/3 of children with cutaneous mastocytosis have no evidence of disease (no skin lesions or symptoms) by their late teen years or early adulthood. Many other children have improvement of symptoms and signs without completing growing out of their condition.

Children with mastocytosis often have some unusual things in their bone marrow biopsies. They often have clusters of mast cells and eosinophils with other cells in their bone marrow. However, the mast cells in those clusters are often normal mast cells and do not have the same markers we see in adults. Many of these children have more mast cells in their bone marrow biopsies than adults with mastocytosis. However, unless the biopsy shows true SM, it does not affect prognosis for the children. Children may have unusual things in their bone marrow biopsies but still go on to grow out of it.

The exception is if the child has true SM. Children with true SM do not grow out of their disease.

Children with mastocytosis often have symptoms that affect multiple organ systems, not just their skin. Abdominal pain and bone pain are often reported. Systemic symptoms do not tell us whether or not the child has SM or whether or not they will grow out of their disease.

An NIH study that included 105 children with mastocytosis found that children with normal baseline tryptase tests had negative bone marrow biopsies. It also found that a tryptase level elevated after anaphylaxis or a bad reaction did not signify that the child had SM. However, they did find that all children with SM had internal organ swelling. Most children with SM were positive for the CKIT D816V mutation.

There are no studies yet on the differences between adults and children with MCAS. There are enough anecdotal findings to suggest that children with MCAS do not grow out of their disease the way children with CM sometimes do.

For more detailed reading, please visit these posts:

Childhood mastocytosis: Update

Progression of mast cell diseases (Part 5)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 29

37. What is the difference between mast cell activation syndrome, mast cell activation disorder, and mast cell activation disease?

Mast cell activation syndrome refers to a condition associated with very specific symptoms associated with mast cell mediator release. There are multiple sets of criteria for diagnosing mast cell activation syndrome so it is hard to be more specific than this. Generally, patients with MCAS have mast cell symptoms, evidence of mast cell activation seen in urine or blood tests, and response to medications that manage symptoms seen with mast cell activation. Several variations of mast cell activation syndrome now have ICD-10 codes, an important step towards becoming more accepted diagnoses.

Mast cell activation disorder is usually used interchangeably with mast cell activation syndrome. However, when pluralized as mast cell activation disorders, it sometimes refers broadly to any disease characterized by mast cell activation, like mast cell activation syndrome and systemic mastocytosis.

Mast cell activation disease is a broad term used for any disease characterized by mast cell activation, like mast cell activation syndrome and systemic mastocytosis.

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 28

36. Is MCAS less serious than SM?

No.

There is a lot of literature presenting data on SM. There is a lot less on MCAS. This is largely because of how recently it has described and the fact that different sets of criteria make it impossible to do large scale studies as have been done with SM. So it’s hard to objectively compare the data because the same volume just doesn’t exist yet.

Many providers and researchers think of MCAS as a form of “preclinical SM”. This term was tossed around in the early 2000s by SM researchers who found patients that seemed to have SM but didn’t meet the criteria for it. There were a few presentations in which an image was shown of a line with the different types of SM shown.

From left to right, the line read:
Preclinical SM/Indolent SM/Smoldering SM/Aggressive SM/Mast cell leukemia

Based upon this figure, and the fact that we are trained to look at lines like this as continuum that either increases or decreases in order, many people latched onto “preclinical SM” (like MCAS) as being the least dangerous. Importantly, the figure refers to the increasing danger of permanent organ damage by mast cells ending up in organ tissues. It does NOT refer to the danger of anaphylaxis.

Indolent systemic mastocytosis (ISM) is the least dangerous form of SM and by far the most common. When people ask if MCAS is less dangerous than SM, they usually mean is MCAS less dangerous than ISM. A couple of small study groups have found that prevalence of anaphylaxis in MCAS is less frequent than in ISM. However, this comparison is flawed. Many people have known they have SM for 20+ years. MCAS hasn’t even been a viable diagnosis for 10 years. MCAS is also less likely to be diagnosed due to decreased exposure on the part of many providers. Many MCAS patients are diagnosed with idiopathic anaphylaxis instead so you’re not really looking at a robust population of MCAS patients in these studies.

ISM has a normal lifespan. It is treated the same way as MCAS and the two conditions have remarkably few differences beyond very specific markers that show the body making too many sloppy mast cells.

Some MCAS patients have protracted anaphylaxis and a normal baseline of very serious daily symptoms. It is my personal opinion that the anaphylaxis episodes I have observed in many MCAS patients can be a lot worse than you see in ISM. MCAS patients also have a harder time finding treatment. While ISM patients certainly run into unknowledgeable providers, it is my experience that having an ISM diagnosis is more helpful for facilitating treatment than an MCAS diagnosis.

We need time in order for larger studies and more unifying MCAS criteria to emerge but I am certain that these will follow. MCAS is at least as dangerous as ISM, if not more. Both MCAS and ISM are less dangerous than SSM, ASM and MCL.

For more detailed reading, please visit these posts:
The Provider Primer Series: Mast cell activation syndrome (MCAS)
The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The MastAttack 107: The Layperson’s Guide to Understand Mast Cell Diseases, Part 27

35. Why are there different sets of criteria for mast cell activation syndrome? What are the differences between them?

To answer this fully, we need to first discuss the history behind some terms.

Mast cell activation syndrome was first used to describe episodes of mast cell mediator release symptoms in a paper published in 2007 (Akin 2007). Specifically, the term was used to detail the experience of patients who had symptoms we commonly associated with mast cell activation, like flushing, hives, and low blood pressure.

However, the patients in this study were all found to have some features of systemic mastocytosis. While they had some of the criteria for an SM diagnosis, they didn’t meet all the criteria. These patients sort of looked like SM and quacked like SM but would not cleanly meet the diagnostic criteria. So the author of that paper made a separate diagnostic category for them. He called it monoclonal mast cell activation syndrome.

The use of the word “monoclonal” is VERY important here. Monoclonal is a medical term that is associated with the body making too many cells at once so that the cells that are made don’t work correctly. Systemic mastocytosis is a condition in which the body makes too many cells at once that don’t work right. It is a monoclonal disorder. So the author of that paper in 2007 is linking monoclonal mast cell activation syndrome to systemic mastocytosis. He thought of it as sort of a “pre-SM” or “early SM”.

Shortly after that 2007 paper was released, another school of thought was proposed by different groups about the nature of mast cell activation syndrome. These groups also linked the term mast cell activation syndrome to symptoms of mast cell activation, like flushing, hives, and all the rest. However, they did NOT link mast cell activation syndrome to monoclonality. This means that these researchers felt that mast cell activation syndrome could be present without a condition where you make too many sloppy cells like systemic mastocytosis. So patients with no evidence of systemic mastocytosis could still have mast cell activation syndrome according to these groups. The two major groups that believed MCAS was distinct from SM were led by Afrin/Molderings and Castells.

Let’s recap:

In 2007, Akin described mast cell activation syndrome as something that happened only in patients that had some evidence of systemic mastocytosis but not enough to be diagnosed with systemic mastocytosis. In order for this group to diagnose you with mast cell activation syndrome, you had to have evidence of systemic mastocytosis. It was an add on diagnosis to SM, sort of like SM with really bad symptoms.

In the years that followed, two groups, led by Afrin/Molderings and Castells, described mast cell activation syndrome as something that was distinct from systemic mastocytosis and could be found in anyone, even if they had no evidence of systemic mastocytosis at all.

Okay. So these two groups agreed that MCAS could happen to anyone. But they differ greatly in how they think MCAS can be diagnosed. For these groups, MCAS is NOT an add on diagnosis to systemic mastocytosis. It is a standalone diagnosis and entity.

So if the term MCAS was already being used, why didn’t the other groups just call their diagnosis something different? There isn’t a good answer to this but it is super common. Things are much more fluidly changing in the time between coining a term and having the diagnosis accepted by a large organization like the CDC so that your insurance can bill for treatment for that diagnosis. It would be great if everyone just used different names for their variants but this just doesn’t always happen.

Castells feels that in order to be diagnosed with MCAS, you have to show mast cell mediator symptoms, response to medications to treat mast cell activation, and evidence of mast cell activation. You also have to rule out every other possible cause of mast cell activation. Keep in mind that your mast cells are normally activated for lots of reasons so this can really difficult to do.

Additionally, this school considers mast cell activation to be evidenced only by elevation of serum tryptase, 24 hour urinary n-methylhistamine or 24 hour urinary prostaglandin D2 or 9a,11b-prostaglandin F2. So if none of these mediators are high, the patient doesn’t meet the criteria for diagnosis.

Afrin’s criteria are harder to explain because he believes that you should provisionally be diagnosed with mast cell activation disease, which can be a few different things, and then it should be narrowed down to mast cell activation syndrome or another mast cell condition.

The key difference between Afrin’s criteria and Castells’ are that he accepts elevated levels of several other mast cell chemicals to prove mast cell activation. Afrin counts toward diagnosis elevation of serum tryptase, 24 hour urinary n-methylhistamine, serum or 24 hour urinary prostaglandin D2 or 9a,11b-prostaglandin F2, 24 hour urinary leukotriene E4, heparin in blood, and chromogranin A in blood. All of these are released by mast cells. But some of them are released by other cells too so it’s not as easy to say for sure that mast cells cause the elevations. Additionally, some of these mediators are REALLY difficult to measure accurately, like heparin. So some people feel that these tests are less reliable to indicate mast cell activation alone.

Let’s talk about puppies for a second because when things get tough, just find a puppy and things will be cool from there on out.

Let’s present these three schools of thought on MCAS as puppies.

Let’s say that Akin is saying that all dogs with 10 spots on them have SM. He’s saying that dogs with some spots, but less than 10, have MCAS. He is also saying that dogs with NO spots CANNOT have MCAS.

Castells is saying that it doesn’t matter how many spots the dog has but it has to have either blue or green eyes to have MCAS. She doesn’t think the MCAS is related to spots but that it is related to specific eye color.

Afrin is saying that it doesn’t matter how many spots the dog has, or what color eyes. He will accept eyes of many other colors if the dog has a lot of symptoms that look like mast cell activation or respond to medications to treat mast cell activation.

I have simplified this as much as possible so it’s easier to understand. For that reason, I have omitted a lot of things. I am in no way saying that what I described here represents everyone’s experience. I am not saying that at all.

If you want my opinion on what MCAS is, and I’m inclined to think you do because you’re on my website reading my thoughts about mast cell disease, I feel that the evidence points strongly towards a space that blends both Afrin’s and Castells’ points. I feel that we should use more mast cell mediators than just serum tryptase, 24 hour urinary n-methylhistamine, serum or 24 hour urinary prostaglandin D2 or 9a,11b-prostaglandin F2. But I personally find the reliability of tests for heparin level to be very problematic and elevations of chromogranin A can be from so many things. I am not AT ALL saying that people diagnosed with these elevated markers do not have MCAS. I professionally develop diagnostics and these tests are just not great.

I also don’t think there’s enough evidence yet to say that mast cell disease can be proven with a biopsy demonstrating a certain number of mast cells per hpf (high powered field, this is a measurement we use for counting things we see under a microscope). I think it is very suggestive of inflammation and mast cell activity. But there are MANY instances in which normal, healthy, asymptomatic patients have a bunch of mast cells/hpf in their biopsies when they are used in studies.

So I’m solidly in the MCAS is its own entity group but don’t fall evenly into one group or the other regarding diagnosis.

Regarding treatment, I land more squarely with Afrin. I believe that if you have tried all of the conventional treatments and continue to have life threatening episodes, you should be able to try more drastic treatments provided you are well supervised by a knowledgeable provider. This is my personal opinion and in no way reflects the views of my employer. I think that if you are constantly anaphylaxing, or have no safe foods, or have dystonic seizures, or can’t stand up, and you have gone through a long list of “reasonable treatments” that you have a right to try to preserve your life and the quality thereof with any means available.

So, yea. MCAS is a can of worms. But we owe it to MCAS patients to have these awkward discussions even though it’s, well, awkward. Patients are falling through the cracks and we owe it to them to identify what criteria would let us catch them so they can get diagnosed and treated sooner.

I’ve tried hard to explain this objectively but if I haven’t done great, let me know in the comments.

For more detailed reading, please visit these posts:
The Provider Primer Series: Mast cell activation syndrome (MCAS)
MCAS: Differing criteria among experts

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Disease, Part 23

I answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

  1. Is mast cell activation the same as mast cell activation syndrome?
  • No.
  • This is the single most important clarification I make as an educator. It is crucial to understand that they aren’t the same thing, especially if you research mast cell activation syndrome online.
  • Mast cell activation is a normal and healthy process. Mast cell activation mostly means that they are ready to release chemicals in response to signals from inside the mast cell or from other cells. It is one of the major ways mast cells carry out their normal functions, like fighting infections, healing the body post trauma, and regulating the menstrual cycle.
  • Many things activate mast cells to tell mast cells to act in their normal functions. Bacteria, viruses, fungi, cancer cells, diarrhea, pain, surgery, physical or emotional stress, and many other things all activate mast cells normally. It is not surprising that these things activate mast cells because they should activate them.
  • Sometimes mast cells overreact to signals to activate, like in allergies and anaphylaxis.
  • The reason mast cell activation is a problem in mast cell disease is because mast cells respond way too strongly to activation signals. They release too many chemicals too often.
  • The other reason mast cell activation is also a problem in mast cell disease is because they become too easily activated.
  • Think of mast cells like houses. Like any house, they have doors. In healthy people, you need a lot of people knocking on the doors and windows at the same time to get the mast cell to open the doors and release chemicals. In mast cell patients, one person can knock a few times and all the doors open and release chemicals at once.

For more information, please visit this post:

The Provider Primer Series: Introduction to Mast Cells

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 15

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.
23. Is mast cell disease progressive?
• No, mast cell disease is not inherently progressive. Many patients live their entire lives with the same diagnosis.
• “Progressive” is not the same thing as “changing.” The way mast cell disease can change over time and often does.
• “Progressive” has a very specific meaning in this context. It means movement from one diagnostic category to another, essentially changing your diagnosis to a more serious form of mast cell disease.
• We do not have studies yet on whether or not MCAS “becomes” SM. However, we know that many people live with MCAS for decades without evidence of SM.
• There are several subtypes of systemic mastocytosis. In order of increasing severity, they are: indolent systemic mastocytosis; smoldering systemic mastocytosis; systemic mastocytosis with associated hematologic disease; aggressive systemic mastocytosis; and mast cell leukemia.
• The relative danger of systemic mastocytosis with associated hematologic disease (SM-AHD) when compared with other forms of systemic mastocytosis varies wildly. SM-AHD is when you have SM and another blood disorder where your body makes way too many cells. The other blood disorder is an important factor in life expectancy and risk of organ damage so it is difficult to compare it to other forms of mastocytosis.
• For patients with indolent systemic mastocytosis, in the 5-10 years following diagnosis, about 1.7% of patients progressed to smoldering mastocytosis, aggressive systemic mastocytosis, or mast cell leukemia.
• For patients with indolent systemic mastocytosis, in the 20-25 years following diagnosis, about 8.4% of patients progressed to smoldering mastocytosis, aggressive systemic mastocytosis, or mast cell leukemia.
• For patients with indolent systemic mastocytosis, one study found that roughly 8% of patients progressed to smoldering systemic mastocytosis.
• For patients with indolent systemic mastocytosis, two studies found that roughly 3% and 4% of patients progressed to aggressive systemic mastocytosis.
• For patients with indolent systemic mastocytosis, about 0.6% of patients progressed to acute leukemia (mast cell leukemia or acute myelogenous leukemia)..
• For patients with smoldering systemic mastocytosis, about 18% of them progressed to aggressive systemic mastocytosis or mast cell leukemia.
• For patients with aggressive systemic mastocytosis, about 6.5% of them progressed to acute leukemia (mast cell leukemia or acute myelogenous leukemia).
• For patients with systemic mastocytosis with associated hematologic disease, about 13% of them progressed to acute leukemia (mast cell leukemia or acute myelogenous leukemia).

For more detailed reading, please visit these posts:

Progression of mast cell diseases: Part 2

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 14

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

22. Is MCAS an early form of SM?

• MCAS is not viewed as an early form of SM but the diagnosis of MCAS may precede a later diagnosis of SM.
• In the last few years, we have learned a lot about the genetics associated with mast cell diseases and how it occurs in families. As a result, we are beginning to understand that mast cell diseases occur more along a spectrum than as distinct categories. This means that there is a lot of overlap between conditions.
• While it is certainly not a new disorder, MCAS is a pretty recent diagnostic entity. The last decade has seen a large increase in diagnosis as it has been more frequently described. Because of how new it is, and also the fact that there aren’t uniform criteria for what MCAS is, there will be a level of uncertainty about how this disease tends to progress for some time.
• That uncertainty aside, we know that at least some patients with a long history of MCAS have continued to have symptoms without developing markers of systemic mastocytosis.
• However, some patients with history of MCAS do develop markers of systemic mastocytosis.
• Many patients do not receive bone marrow biopsies when they are diagnosed with MCAS because there is not always a reason to have one. It often doesn’t affect treatment. If there is no sign of organ damage, the patient has a negative blood test for the CKIT D816V mutation, and their baseline tryptase is below 20 ng/mL, most doctors do not order a bone marrow biopsy. This means that some patients who are diagnosed with MCAS may have had SM all along but it wasn’t found until a biopsy was performed later.
• In 2007, monoclonal mast cell activation syndrome was described in scientific literature. This condition is diagnosed when a patient meets some criteria of systemic mastocytosis but not enough for a diagnosis of SM.
• Monoclonal mast cell activation syndrome is more often viewed as a “pre-SM”. I personally view it this way. Before it had a name, researchers called it “pre-diagnostic SM.” Literally, SM before they could diagnose it as SM.

For more detailed reading, please visit these posts:

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, part 7

I have answered the 107 questions I have been asked most in the last four years. No jargon. No terminology. Just answers.

 

13. What do these biopsy tests look for?
• They look for the shape, quantity, and distribution of mast cells.
• They also look for specific proteins on the outside of mast cells and tissue damage around mast cells.
• Systemic mastocytosis and cutaneous mastocytosis are generally diagnosed by biopsy. With very, very few exceptions, you cannot meet the criteria for systemic mastocytosis without having a positive biopsy. Sometimes people with monoclonal mast cell activation syndrome are diagnosed by having a biopsy that looks like a very early phase of systemic mastocytosis.
• The diagnostic criteria for mast cell activation syndrome are hotly contested. Most doctors do not use biopsies to diagnose MCAS because there are not uniform criteria. Some doctors feel that more than 20 mast cells in a field when you look through the microscope is a sign of MCAS.
• Cutaneous mastocytosis is having too many broken mast cells in your skin. For this condition, they are looking for either 20 mast cells to be present in the microscope field (hpf) when looking at the skin, or for there to be at least one cluster of at least fifteen mast cells.
• Clustering is a very important feature of mastocytosis. When mast cells bunch together in a cluster, it is easier to damage the tissue. They are essentially punching holes in the tissue by clustering.
• Systemic mastocytosis is having too many broken mast cells made by the bone marrow. Systemic mastocytosis is usually diagnosed by a positive bone marrow biopsy. However, sometimes people are diagnosed by biopsies of other organs. Skin biopsy is NOT enough to diagnose systemic mastocytosis.
• For systemic mastocytosis, there are three key things they are looking for in the biopsy.
• They are looking for at least one cluster of at least fifteen mast cells.
• They are looking for some of the mast cells to be shaped like spindles, sort of smushed at the ends and round in the middle. You see this shape a lot when cells are trying to stick together in a cluster.
• They are looking for special proteins that are only found when a patient has systemic mastocytosis or monoclonal mast cell activation syndrome. They are called CD25 and CD2. These are like flags that the mast cells fly to tell us they are broken. One of them, CD25, actually helps mast cells cluster together.
• In biopsies, they usually also look for the protein CD117. This is a normal flag for mast cells to fly and just allows us to know that we are looking at mast cells.

For more detailed reading, please visit these posts:

The Provider Primer Series: Management of mast cell mediator symptoms and release

The Provider Primer Series: Mast cell activation syndrome (MCAS)

The Provider Primer Series: Cutaneous Mastocytosis/ Mastocytosis in the Skin

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (ISM, SSM, ASM)

The Provider Primer Series: Diagnosis and natural history of systemic mastocytosis (SM-AHD, MCL, MCS)