The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 21

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

30. Why does my skin get red and itchy?
• Flushing is one of the hallmark signs of mast cell disease. It is sometimes the symptom that drives providers to look at mast cell disease as a potential diagnosis.
• Mast cells make and release many chemicals. These chemicals are commonly called mediators because they mediate many reactions in the body that affect the body in many different ways.
• Some mast cell mediators make blood vessels relax. The vessels get a little wider. When the vessels get bigger, the ones under the skin get closer to the skin. Because those vessels show red from the blood in them, the blood is closer to the skin so the skin looks red.
• Flushing is often asymmetrical. There isn’t a hard and fast reason for why this happens but is likely caused by local mast cell mediator release. Essentially, if the mast cells on the right side of your face get irritated, the right side is more likely to flush than the left side.
Flushing is mostly mediated by prostaglandin D2. Aspirin is often prescribed for mast cell patients that tolerate it because aspirin blocks cells from making prostaglandins. This is because aspirin interferes with the molecule that manufactures them. Many other substances can also interfere with this, including other NSAIDs. Another class of drug, 5-lipoxygenase inhibitors, can also stop production of prostaglandins in a different way.
• To a lesser extent, histamine contributes flushing and antihistamines sometimes help.
What exactly causes itching is still not entirely clear. There are special little places in your body called itch receptors. When they notice something itchy, it’s their job to raise the alarm. We think that mast cells carry the message from those places to the nervous system that then spread the itch signal. It’s like carrying the flame of one candle from the itch receptor to the nervous system, which sets the forest on fire.
• Hydroxyzine and other antihistamines are often used for itching. Corticosteroids like prednisone, either oral or topical, may help. Also, medications that interfere with prostaglandin production, like an NSAID or a 5-lipoxygenase inhibitor, sometimes help.

For more detailed reading, please visit these posts:
The Provider Primer Series: Management of mast cell mediator symptoms and release
Prostaglandins and leukotrienes
Mast cell mediators: Prostaglandin D2 (PGD2)

The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 3

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

6. What symptoms does mast cell disease cause?

  • Mast cell disease can cause just about any symptom. Seriously.
  • Mast cell disease can cause symptoms in every system of the body. This is because mast cells are found in tissues throughout the body. They are intimately involved in lots of normal functions of the human body. When mast cells are not working correctly, lots of normal functions are not carried out correctly. When this happens, it causes symptoms. In short, mast cells can cause symptoms anywhere in the body because they were there already to help your body work right.
  • Skin symptoms can include flushing, rashes, hives (urticaria), itching, blistering, and swelling under the skin (angioedema).
  • GI symptoms include nausea, vomiting, diarrhea, constipation, problems with the GI not moving correctly in general (GI dysmotility), swelling of the GI tract, chest and abdominal pain, belching, bloating, discolored stool, excessive salivation, dry mouth, and trouble swallowing.
  • Cardiovascular symptoms include high or low blood pressure, fast or slow heart rate, irregular heartbeat, and poor circulation.
  • Neuropsychiatric symptoms include brain fog, difficulty concentrating, difficulty sleeping at night, excessive tiredness during the day, grogginess, anxiety, depression, tremors, numbness, weakness, burning and tingling (pins and needles), hearing loss, and auditory processing (difficulty understanding what was said to you).
  • Genitourinary symptoms include bladder pain, painful urination, painful intercourse/sexual activities, painful or irregular menstrual cycle (periods), and excessive or inadequate urination (too much or too little urine produced).
  • Respiratory symptoms include cough, excessive phlegm, wheezing, runny nose, sinus congestion, sneezing, and swelling of the airway.
  • General symptoms include fatigue, lack of stamina, difficulty exercising, itchy or watery eyes, and bruising easily.
  • There are some additional symptoms that I have observed in a large number of people that are not classically considered mast cell symptoms, but I now firmly believe them to be. One is fever. I think discoloration of the skin may be mast cell related for some people. Another is dystonia, involuntary muscle contraction, which can mimic appearance of a seizure. There are also different seizure-type episodes that may occur due to the nervous system being overactive. I am reluctant to call them pseudoseizures because that term specifically means they are caused as a result of mental illness. I have no evidence that these seizure-type episodes in mast cell patients occur due to mental illness. I personally refer to them as “mast cell derived seizures.” (For people who are wondering, I have been heavily researching this phenomenon and have some theories about why this happens. It’s not fleshed out enough yet to post but it’s on my think list.)
  • Having mast cell disease can make you more likely to have other conditions that cause symptoms.
  • I’m sure there are other symptoms I have forgotten to mention.

7. Why are skin and GI symptoms so common?

  • The skin has a lot of mast cells relative to other tissues. Your skin also comes into contact with lots of things in the environment. Think about the things your skin touches on a daily basis! It makes sense that it would get the exposure so skin symptoms can be common. Additionally, some of the chemicals mast cells release can cause fluid to become trapped in the skin. For these reasons, symptoms affecting the skin are pretty common.
  • The GI tract also has a lot of mast cells relative to other tissues. Your GI tract also comes in contact with lots of things in the environment. Let’s think about this for a minute. Your GI tract is essentially one long tube through your body. You put things from the environment in your GI tract at the top and they come back out the bottom of the tract. In a way, your GI tract is kind of like the outside of the inside of your body.
  • This is the analogy I learned in anatomy and physiology class to visualizing the GI tract as the outside of the inside of the body. Think of the body as a donut. (A low histamine, fully allergy friendly, requires no GI motility, wonderful donut.) Now think of the GI tract as the donut hole. You can put your finger through the hole in the middle of the donut. Only that center part of the donut will touch your finger. This is kind of like putting food throughout the GI tract. That food only touches a very small part of the body as it passes through.
  • Since what we put into our mouths (or other GI openings) is from the outside, your body has many mast cells in the GI tract to protect the body. Some of the chemicals mast cells release can cause fluid to become trapped in the layers of GI tissue. Some of the medications we take for mast cell disease can affect the GI tract. Some of them change how much acid we make in our stomachs. Some of them slow down the GI tract. A few of them speed it up or make the GI tract more fragile. For these reasons, symptoms affecting the GI tract are very common.

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)

The Provider Primer Series: Relevance of mast cells in common health scenarios

 

Symptom Cough
Role of mast cells Several mast cell mediators contribute to airway inflammation and subsequent symptoms including cough:

•             Histamine promotes bronchoconstriction, excessive production of mucus, and airway edema.[i]

•             Prostaglandin D2 promotes bronchoconstriction, mucus production, and airway edema.[i]

•             Leukotrienes C4 and D4 and chymase also contribute to mucus production and airway edema.[i]

•             Tryptase promotes overall increased reactivity of the airway.[i]

Chronic airway inflammation, as in asthma, is sometimes associated with increased mast cell population in pulmonary tissues.[i]

Mast cells remain activated in inflamed airways.[i]

Impact of condition on mast cells Mast cell activation can occur as a result of the physical stimuli such as coughing[ii].

Pain can trigger mast cell activation[iii].

Notes regarding condition treatment Dextromethorphan can trigger mast cell degranulation[iv].

Codeine and derivatives can trigger mast cell degranulation[v].

Beta-2 adrenergic agonists, inhaled and oral steroids, and inhaled cromolyn are frequently used in mast cell patients[vi].

Notes regarding mast cell treatment Antihistamines, leukotriene receptor antagonists, and COX inhibitors are routinely taken by mast cell patients and can provide relief.[vii]

Racemic epinephrine can provide relief of pulmonary symptoms.[viii]

Special considerations for mast cell patients Chronic dry, unproductive cough sometimes occurs in mast cell patients.[ix]

Mast cell patients frequently have reactive airways.[ix]

Mast cells can produce and release prostaglandin E2, a mediator that participates in asthmatic inflammation and cough[x].

Prostaglandin E2 can also downregulate or promote mast cell degranulation via binding at prostaglandin E2 receptors on mast cell surface[x].

 

Symptom Sore throat
Role of mast cells Pain can trigger mast cell activation.[iii]
Impact of condition on mast cells Mast cell driven nasal congestion can result in postnasal drip can irritate the throat.[ix]

Mast cell irritation of the throat can present similarly to infection by Streptococcus spp. or other pathogen. Cultures should be taken to properly evaluate for infection.[ix]

Viral, bacterial and fungal infection will activate mast cells through toll like receptors and through perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment Acetaminophen is recommended for pain relief in mast cell patients.[iv]
Notes regarding mast cell treatment Antihistamines and COX inhibitors are routinely taken by mast cell patients and can provide relief.[vi]
Special considerations for mast cell patients Angioedema of the throat driven by mast cell disease is always a consideration in mast cell patients. If angioedema secondary to mast cell disease impinges upon airway, epinephrine and subsequent anaphylaxis treatments should be undertaken.[vii]

Oral allergy syndrome should be considered.[ix]

 

Symptom Rash
Role of mast cells Acute urticaria is usually driven by mast cell and basophil activation through IgE or non-IgE pathways.[xi]

Mast cell mediators histamine, leukotrienes and platelet activating factor contribute to itching.[xii]

Impact of condition on mast cells Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Non-mast cell driven conditions causing skin rashes can irritate mast cells in the skin.[xii]

Pain can trigger mast cell activation.[iii]

Notes regarding condition treatment Some -azole antifungals can induce mast cell degranulation.[xiv]
Notes regarding mast cell treatment Antihistamines and steroids, topical or systemic, and topical cromolyn can provide relief.[xii]
Special considerations for mast cell patients Mediator release by activated mast cells can produce systemic symptoms.[x]

In patients with a history of mast cell disease, mastocytosis in the skin should be considered.

o             Cutaneous mastocytosis accounts for approximately 90% of mastocytosis cases.[xii]

o             Cutaneous mastocytosis lesions demonstrate Darier’s sign, a wheal and flare reaction to touch.[xii]

o             A skin biopsy is necessary to confirm a diagnosis of cutaneous mastocytosis.[xii]

o             Patients with adult onset cutaneous mast cell lesions are usually later found to have systemic mastocytosis.[xii]

 

Symptom Fever
Role of mast cells Mast cells can produce prostaglandin E2.[x]

Mast cells can produce and release several pyrogens, including IL-1α, IL-1β, IL-6, IL-8, TNF, interferon-α, interferon-β, and interferon-γ.[x]

Impact of condition on mast cells Prostaglandin E2 can also downregulate or promote mast cell degranulation via binding at prostaglandin E2 receptors on mast cell surface.[x]

Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment NSAIDS can trigger mast cell degranulation. Some mast cell patients are unable to take them.[xv]

Acetaminophen is generally recommended for use in mast cell patients.[iv]

Notes regarding mast cell treatment COX inhibitors are routinely taken by mast cell patients and may provide relief.[vi]
Special considerations for mast cell patients

 

Symptom Earache
Role of mast cells Mast cells are involved in the transmission of pain stimuli, including nerve pain.[iii]

Mast cells are involved in sensorineural hearing loss and tinnitus.[ix]

Impact of condition on mast cells Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment NSAIDS can trigger mast cell degranulation. Some mast cell patients are unable to take them.[xv]

Acetaminophen is generally recommended for use in mast cell patients.[iv]

Steroids (local and systemic) can stabilize mast cells.[vi]

Notes regarding mast cell treatment COX inhibitors are routinely taken by mast cell patients and may provide relief.[vi]

Antihistamines can provide relief for vestibular symptoms.[vi]

Special considerations for mast cell patients Hearing loss, tinnitus and hyperacusis sometimes occur in mast cell patients.[ix]

Sensorineural hearing loss of unknown origin has been documented in mast cell patients.[ix]

Some mast cell patients also have Ehlers Danlos Syndrome which can cause conductive hearing loss.[ix]

Mast cell disease can also cause auditory processing disorder.[ix]

Red ears are a common sign of mast cell activation. Sometimes, only one ear is affected.[ix]

 

Symptom Stomachache
Role of mast cells Mast cells are commonly found in the GI tract.[xvi]

Mast cell activation is involved in a number of GI conditions, including inflammatory bowel disease, ulcerative colitis and food allergies.[xvi]

Mast cell activation can cause chronic diarrhea, pseudoobstruction, obstruction, dysmotility, constipation, nausea, vomiting, and visceral GI pain.[xvi]

Impact of condition on mast cells GI inflammation can recruit mast cells to inflamed tissues.[xvi]

GI inflammation can trigger mast cell mediator release.[xvi]

Pain can trigger mast cell activation.[iii]

Viral, bacterial and fungal infection will activate mast cells via toll like receptors and perpetuated inflammatory signaling.[xiii]

Notes regarding condition treatment
Notes regarding mast cell treatment Histamine H2 blockers and PPIs are commonly taken by mast cell patients and can provide relief.[vi]
Special considerations for mast cell patients Mast cell patients can experience a wide array of severe GI symptoms with or without dense infiltration of GI tract by mast cells.[ix]

 

[i] Cruse G, Bradding P. (2016). Mast cells in airway diseases and interstitial lung disease. European Journal of Pharmacology 778, 125-138.

[ii] Zhang D, et al. (2012). Mast-cell degranulation induced by physical stimuli involves the activation of transient receptor-potential channel TRPV2. Physiol Res, 61(1):113-124.

[iii] Chatterjea D, Martinov T. (2015). Mast cells: versatile gatekeepers of pain. Mol Immunol, 63(1),38-44.

[iv] Dewachter P, et al. (2014). Perioperative management of patients with mastocytosis. Anesthesiology, 120, 753-759.

[v] Brockow K, Bonadonna P. (2012). Drug allergy in mast cell disease. Curr Opin Allergy Clin Immunol, 12, 354-360.

[vi] Molderings GJ, et al. (2016). Pharmacological treatment options for mast cell activation disease. Naunyn-Schmiedeberg’s Arch Pharmol, 389:671.

[vii] Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

[viii] Walsh P, et al. (2008). Comparison of nebulized epinephrine to albuterol in bronchiolitis. Acad Emerg Med, 15(4):305-313.

[ix] Afrin LB. (2013). Diagnosis, presentation and management of mast cell activation syndrome. Mast cells.

[x] Theoharides TC, et al. (2012). Mast cells and inflammation. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease, 1822(1), 21-33.

[xi] Bernstein JA, et al. (2014). The diagnosis and management of acute and chronic urticaria: 2014 update. J Allergy Clin Immunol, 133(5):1270-1277.

[xii] Hartmann K, et al. (2016). Cutaneous manifestations in patients with mastocytosis: consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma and Immunology; and the European Academy of Allergology and Clinical Immunology. Journal of Allergy and Clinical Immunology, 137(1):35-45.

[xiii] Sandig H, Bulfone-Paul S. (2012). TLR signaling in mast cells: common and unique features. Front Immunol, 3;185.

[xiv] Toyoguchi T, et al. (2000). Histamine release induced by antimicrobial agents and effects of antimicrobial agents on vancomycin-induced histamine release from rat peritoneal mast cells.  Pharm Pharmacol, 52(3), 327-331.

[xv] Grosman N. (2007). Comparison of the influence of NSAIDs with different COX-selectivity on histamine release from mast cells isolated from naïve and sensitized rats. International Immunopharmacology, 7(4), 532-540.

[xvi] Ramsay DB, et al. (2010). Mast cells in gastrointestinal disease. Gastroenterology & Hepatology, 6(12): 772-777.

 

The Provider Primer Series: Cutaneous mastocytosis/ Mastocytosis in the skin

Mast cell disease: Categories

  • Mast cell disease is the collective term given to several distinct conditions mediated by mast cell dysfunction.  Speaking broadly, mast cell disease has two forms: mastocytosis, a clonal disease marked by excessive proliferation and infiltration of mast cells; and mast cell activation syndrome (MCAS), a disease that presents similarly to mastocytosis but demonstrates no clear indication of excessive proliferation. In addition, monoclonal mast cell activation syndrome (MMAS) can be viewed as straddling the two groupings with markers of clonality but minimum evidence to suggest overproduction of mast cells[i].
  • Mastocytosis has two forms: cutaneous, in which excessive mast cell infiltration is confined to the skin; and systemic, in which an organ that is not skin that is affected by excessive mast cell infiltration. Patients with systemic mastocytosis (SM) often have cutaneous mastocytosis; in this instance, this is called systemic mastocytosis with mastocytosis in the skin[ii].

Mastocytosis in the skin

  • Cutaneous mastocytosis (CM) is a proliferative condition marked by increased mast cell infiltration of the skin.  There are three subvariants of cutaneous mastocytosis: maculopapular cutaneous mastocytosis (MPCM), formerly known as urticarial pigmentosa (UP); diffuse cutaneous mastocytosis (DCM); and solitary mastocytoma of skin[ii].
  • Mast cell density in lesions is usually increased 4-8x above the density in healthy controls. However, some patients have mast cell density comparable to that in healthy controls[ii].
  • All forms of cutaneous mastocytosis can be found in children. Over 78% present by 13 months and some at birth[v]. Childhood onset CM often resolves by adolescence but not always[ii].
  • Most patients with mast cell lesions in childhood have CM rather than SM. Conversely, most patients who develop these macules in adulthood have systemic mastocytosis with mastocytosis in the skin[ii].
  • MPCM (UP) is overwhelmingly the dominant presentation of mastocytosis in the skin. Over 80% of all mastocytosis patients demonstrate the type of cutaneous involvement[ii].
  • In children, MPCM lesions are usually large and have variable morphology which may change over time. In adults, MPCM often occurs as small red/brown macules and may result in few lesions or cover the majority of the body[iii].
  • Telangiectasia macularis eruptive perstans (TMEP) is described as telangiectatic red macules generally found above the midtrunk. While previously thought to be a discrete entity, TMEP is now recognized as a form of MPCM[ii].
  • DCM is almost exclusively found in children with few adult onset cases. It does not present as discrete lesions but rather generalized erythema. Pachydermia may also be present, as well as darkening of the skin[ii].
  • DCM can be associated with formation of severe bullae from a variety of triggers, including rubbing the skin, infections and teething. Due to mast cell release of heparin, it is not unusual for skin wounds to bleed excessively[ii].
  • A mastocytoma is a low grade mast cell tumor most often found on the skin. It is frequently raised and yellow or brown in color. Touching the lesion usually evokes a strong wheal and flare reaction. Sweating may also occur. Blistering may be present[ii].

Diagnosis of mastocytosis in the skin

  • While a biopsy is the definitive diagnostic method, positive Darier’s sign is present in most children and many adults with mastocytosis in the skin. Use of antihistamines can suppress a positive Darier’s sign[ii].
  • Biopsies from lesional skin should be stained for mast cells using toluidine blue or Giemsa-Wright stain; evaluated for CD117, CD25 and CD2 using IHC; and evaluated for activating mutations in the CKIT gene using PCR or sequencing methods[i] .
Diagnostic criteria for cutaneous mastocytosis  (requires one major and one minor criterion)[iii]
Major Minor
Typical mast cell rash, usually maculopapular, or atypical rash with positive Darier’s sign Dense infiltration by tryptase positive mast cells, >15 mast cells/cluster or >20 mast cells/x40 magnification hpf if not clustered
Activating CKIT mutation detected in biopsy from skin lesion

 

Symptoms and treatment of mastocytosis in the skin

  • Common symptoms localized to the skin include flushing, itching, burning, hives and blistering[iv].
  • Mediator release symptoms can affect other organs regardless of whether or not they have systemic mastocytosis. Flushing, nausea, vomiting, diarrhea and low blood pressure have been reported among other symptoms. Wheezing, shortness of breath and rarely cyanosis may be present. Anaphylaxis can also occur[iii].
  • Treatment for cutaneous mastocytosis/mastocytosis in the skin relies upon histamine blockade with H1 inverse agonists and H2 antagonists; cromolyn sodium; leukotriene antagonists; and PUVA treatment in severe cases[v].
  • In treatment resistant cases, systemic glucocorticoids and topical cromolyn may be used.  In some instances, mastocytomas may be excisedi. Anaphylaxis should be treated with epinephrine per current guidelines[v].

[i] Molderings GJ, et al. (2011). Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. J Hematol Oncol, 4(10), 10.1186/1756-8722-4-10

[ii] Hartmann K, et al. (2016). Cutaneous manifestations in patients with mastocytosis: consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma and Immunology; and the European Academy of Allergology and Clinical Immunology. Journal of Allergy and Clinical Immunology, 137(1), 35-45.

[iii] Valent P, et al. (2007). Standards and standardization in mastocytosis: consensus statements on diagnostics, treatment recommendations and response criteria. European Journal of Clinical Investigation, 37, 435-453.

[iv] Carter MC, et al. (2014). Mastocytosis. Immunol Allergy Clin North Am, 34(1), 10.1016/j.iac.2013.09.001

[v] Castells M, et al. (2011). Guidelines for the diagnosis and treatment of cutaneous mastocytosis in children. Am J Clin Dermatol, 12(4), 259-270.

 

Symptoms, mediators and mechanisms: A general review (Part 1 of 2)

Skin symptoms    
Symptom Mediators Mechanism
Flushing Histamine (H1), PGD2 Increased vasodilation and permeability of blood vessels

Blood is closer to the skin and redness is seen

Itching Histamine (H1), leukotrienes LTC4, LTD4, LTE4, PAF Possibly stimulation of itch receptors or interaction with local neurotransmitters
Urticaria Histamine (H1), PAF, heparin, bradykinin Increased vasodilation and permeability of blood vessels and lymphatic vessels

Fluid is trapped inappropriately between layers of skin

Angioedema Histamine (H1), heparin, bradykinin, PAF Increased vasodilation and permeability of blood vessels and lymphatic vessels

Fluid is trapped inappropriately between layers of tissue

 

Respiratory symptoms    
Symptom Mediators Mechanism
Nasal congestion Histamine (H1), histamine (H2), leukotrienes LTC4, LTD4, LTE4 Increased mucus production

Smooth muscle constriction

Sneezing Histamine (H1), histamine (H2), leukotrienes LTC4, LTD4, LTE4 Increased mucus production

Smooth muscle constriction

Airway constriction/ difficulty breathing Histamine (H1), leukotrienes LTC4, LTD4, LTE4, PAF Increased mucus production

Smooth muscle constriction

 

Cardiovascular symptoms    
Symptom Mediators Mechanism
Low blood pressure Histamine (H1), PAF,  PGD2, bradykinin Decreased force of heart contraction

Increased vasodilation and permeability of blood vessels

Impact on norepinephrine signaling

Change in heart rate

Presyncope/syncope (fainting) Histamine (H1), histamine (H3), PAF, bradykinin Increased vasodilation and permeability of blood vessels

Decrease in blood pressure

Dysfunctional release of neurotransmitters

High blood pressure Chymase,  9a,11b-PGF2, renin, thromboxane A, carboxypeptidase A Impact on renin-angiotensin pathway

Impact on norepinephrine signaling

Tightening and decreased permeability of blood vessels

Tachycardia Histamine (H2), PGD2 Increasing heart rate

Increasing force of heart contraction

Impact on norepinephrine signaling

Arrhythmias Chymase, PAF, renin Impact on renin-angiotensin pathway

Impact on norepinephrine signaling

 

Gastrointestinal symptoms    
Symptom Mediators Mechanism
Diarrhea Histamine (H1), histamine (H2), bradykinin, serotonin Smooth muscle constriction

Increased gastric acid secretion

Dysfunctional release of neurotransmitters

Gas Histamine (H1), histamine (H2), bradykinin Smooth muscle constriction

Increased gastric acid secretion

Abdominal pain Histamine (H1), histamine (H2), bradykinin, serotonin Smooth muscle constriction

Increased gastric acid secretion

Dysfunctional release of neurotransmitters

Nausea/vomiting Histamine (H3), serotonin Dysfunctional release of neurotransmitters
Constipation Histamine (H2), histamine (H3), serotonin (low) Dysfunctional release of neurotransmitters

 

Just a horse

This past spring, I started developing a rash on my back.  It was macular and itchy and swelled and turned red when I touched it. 
“It looks like urticaria pigmentosa except it’s not dark,” one doctor told me.  It’s important to note here that my rash pigmentation has been unusual for my entire life.  I have, on several occasions, had rashes misdiagnosed because they were “too pink” or “too faint.”  I don’t know the reason for this, but it happens.  “I’m sure it’s some kind of mast cell issue, your skin is very reactive,” he followed up.
“That is definitely urticaria pigmentosa,” another doctor told me.  He touched the spots and they puffed up and got itchy.  “See, it has a positive Darier’s sign.”  My skin will urticate will very little provocation so I was not convinced.  But I figured I was probably bound to have UP eventually, so I wasn’t very concerned.
“It is probably a mast cell rash, but you should get it biopsied just in case,” a third doctor told me.  By this point, the rash was all over my back and shoulders.  It was itchy, but not all the time.  I scheduled an appointment with a dermatologist. 
I saw the dermatologist on Thursday.  She took one look at it and said, “Oh, that’s not cutaneous mastocytosis.  That’s a harmless fungal rash.  It’s more common in people who are immunosuppressed.  I’ll give you a cream.”
We had a good laugh over the fact that when you have a rare disease, everyone assumes it is the cause of all your symptoms.  She told me a funny story about a patient with several rare diseases who had a “mysterious rash” that the residents couldn’t identify.  It was tinea versicolor, a very common fungal rash.  The residents had assumed it was something exotic and had not considered more mundane options.
Then there was a small fire in the building while I was dressed only in a gown, educating the visiting PCP about systemic mast cell symptoms from skin reactions.  I threw my clothes on and ran outside as the fire department arrived.  Always lively. 
Mast cell disease is hard to manage in part because it can cause so many problems.  But just because it can cause all of them doesn’t mean it does. 
Mast cell patients are zebras, often many times over.  But even zebras mingle with horses once in a while.