Should Endometriosis Be a Mast Cell Disorder?

Like a lot of people with endometriosis, I have allergies. But the symptoms to my actual allergies — cats and dust mites — are pretty mild. Sometimes my eyes will itch, which I treat with some prescription drops.

But I have a lot of allergy-like reactions during ovulation up until my period. Annoyingly, I'll get red skin bumps that itch or burn. They show up mostly on my upper body, but they can pop up anywhere. My dermatologist says they're probably "some kind of dermatitis." That's the general term for skin inflammation.

My "flares" can look like bug bites, rashes, scratches, or just swollen masses. I stopped trying to figure out what causes them because it seems so random.

The only thing that seems to help are antihistamines like diphenhydramine (Benadryl) and fexofenadine (Allegra). After I did some online research, I found out these are the first line of treatment for mast cell diseases. I don't know if I have a mast cell disease, but I clearly share some of the symptoms.

What symptoms do mast cell diseases cause?

Mast cells are part of your immune system. They send out lots of chemicals when you have an allergic reaction, including histamine and prostaglandins. Mast cells are responsible for all that itching and swelling.

Some people have more mast cells than normal. This can cause a (sometimes deadly) overreaction to actual allergic stimulus, like a bee sting or peanut. My dermatologist tells me my non-allergic allergy-like responses might come from exercise, temperatures changes, strong smells, or hormonal changes. Or maybe they're just idiopathic meaning the cause is unknown.

According to the American Academy of Allergy, Asthma & Immunology, mast cell disorders can cause symptoms such as:^1,2

• Skin redness
• Swelling
• Itching or rash
• Shortness of breath
• Diarrhea
• Vomiting or abdominal cramps
• Fast heart rate
• Dizziness, lightheadedness, or fainting
• Hives on skin exposed to sudden temperature changes, such as hot water
• Uterine cramps/bleeding
• Acid reflux
• Muscle and bone pain

Here are some of my real-life examples that are eerily similar. These things happened during my luteal phase:

• I woke up with a rash on my wrist for no reason. But it that looked and felt like poison ivy.
• Water from a warm or hot shower will sting my back but nowhere else. It'll feel like what I imagine a mild chemical burn feels like. If I look in the mirror right after, I'll see lots of red scratch-like marks on my upper back.
• Once, two insanely itchy, rock-hard bumps formed on my upper arm.  A couple days later, the same thing happened on the bottom of my foot. I still have no idea why.
• I get hives on my chest.
• My nose gets really stopped up.
• My heart beats 20-30 beats faster than normal, at rest.
• I've fallen down from low blood pressure before.
• I get acid reflux.
• My stomach bloats and hurts.
• And of course there's diarrhea.

How are mast cells involved with endo?

A number of studies already show that people with endometriosis have altered immune-related cells in their peritoneal fluid. That's the liquid that coats pretty much all of your abdominal and pelvic organs. Specifically, endo warriors tend to have lots of "macrophages, neutrophils, and dendritic cells." Those are all key players in your immune system. When they're overactive, you get chronic inflammation.³ I've read that it's like the body is constantly trying to heal itself.

As far as I know, endometriosis isn't considered a mast cell disorder. But researchers are looking into the connection. A study published in 2020 in  Frontiers in Psychology shows that people with endo have higher numbers of mast cells in their peritoneal fluid. The study's authors think these mast cells have a hand in both endo-related inflammation and infertility.⁴

What are true mast cell disorders?

Everyone has mast cells in their body. They're triggered in situations like insect stings, medication, or snake bites. But some people have too much mast cell activation or production. That can cause really serious reactions, like anaphylaxis: trouble breathing, passing out, swelling, hives, low blood pressure, serious diarrhea. The situations are what EpiPens are good for.

Mast cell disorders include:

• Mastocytocis. This is a rare genetic condition where your mast cells build up in more than one organ, including in your bone marrow. Kids usually have skin problems that they grow out of. But adults can have systemic problems. Symptoms can be mild or serious.
• Mast cell activation syndrome (MCAS). Mast cells activate and grow in your body because of abnormal signals. You may have multiple episodes of anaphylaxis for unknown reasons.
• Hereditary alpha-tryptasemia. You have an extra copy of a gene that makes tryptase. That's a protein your mast cells make.

How do you find out if you have a mast cell disorder?

No one on my health care team has ever mentioned these to me, but there are skin, blood, urine, and bone marrow tests that'll show certain mast cell markers. Your doctor may also test your liver or give you a genetic test. It's best to talk to someone who has experience treating mast cells disorders. That could be an allergist or immunologist. Ask your doctor for a referral if you're not sure who to go to.

How do you treat overactive mast cells?

It depends on how serious your symptoms are. And you probably already know this, but it's best to avoid anything that triggers your allergic or allergy-like reaction. If you're like me, it can be hard to know what that is. Thankfully, though, my symptoms are more uncomfortable than dangerous.

With that said, medication like antihistamines really helps me. If you have certain mast cell disorders, your doctor might give you stronger medicine.