Mast cell activation syndrome

Mast cell activation syndrome (MCAS) is one type of mast cell activation disorder (MCAD), and is an immunological condition in which mast cells inappropriately and excessively release chemical mediators, resulting in a range of chronic symptoms, sometimes including anaphylaxis or near-anaphylaxis attacks.[1][2][3] Primary symptoms include cardiovascular, dermatological, gastrointestinal, neurological and respiratory problems.[2]

Not to be confused with Mastocytosis.
Mast cell activation syndrome
SpecialtyImmunology (Allergy)

Unlike mastocytosis, another type of MCAD, where patients have an abnormally increased number of mast cells, patients with MCAS have a normal number of mast cells that do not function properly and are defined as "hyperresponsive".[2] MCAS is still a poorly understood condition and is a current topic of research.[4]

Pathophysiology

Mast cell activation can be localized or systemic. MCAS can present with a wide range of symptoms in multiple body systems, these symptoms may range from digestive discomfort to chronic pain, mental issues as well as an anaphylactic reaction ([5] The Mastocytosis Society). Some examples of  tissue specific consequences of mast cell activation include urticaria, allergic rhinitis, and wheezing. Systemic mast cell activation presents with symptoms involving 2 or more organ systems (skin: urticaria, angioedema, and flushing; gastrointestinal: nausea, vomiting, diarrhea, and abdominal cramping; cardiovascular: hypotensive syncope or near syncope and tachycardia; respiratory: wheezing; naso-ocular: conjunctival injection, pruritus, and nasal stuffiness). This can result from the release of mediators from a specific site, such as the skin or mucosal tissue, or activation of mast cells around the vasculature.[6]

Signs and symptoms

MCAS is a condition that affects multiple systems, generally in an inflammatory manner. Symptoms typically wax and wane over time, varying in severity and duration. Many signs and symptoms are the same as those for mastocytosis, because both conditions result in too many mediators released by mast cells.[7] It has many overlapping characteristics with recurrent idiopathic anaphylaxis, although there are distinguishing symptoms, specifically hives and angioedema.[8]

Common symptoms include:[4][9]

  • Dermatological
    • flushing
    • hives
    • easy bruising
    • either a reddish or a pale complexion
    • itchiness
    • burning feeling
    • dermatographism
  • Cardiovascular
  • Gastrointestinal
    • diarrhea and/or constipation, cramping, intestinal discomfort
    • nausea, vomiting
    • swallowing difficulty, throat tightness
  • Respiratory
    • congestion, coughing, wheezing
  • Anaphylaxis If too many mediators are spilt into a patient's system, they may also experience anaphylaxis, which primarily includes: difficulty breathing, itchy hives, flushing or pale skin, feeling of warmth, weak and rapid pulse, nausea, vomiting, diarrhea, dizziness and fainting.

Causes

There are no known causes, but the condition appears to be inherited in some patients.[10] Symptoms of MCAS are caused by excessive chemical mediators inappropriately released by mast cells. Mediators include leukotrienes, histamines, prostaglandin, and tryptase. The condition may be mild until exacerbated by stressful life events, or symptoms may develop and slowly trend worse with time.[4][10]

Diagnosis

MCAS is often difficult to identify due to the heterogeneity of symptoms and the "lack of flagrant acute presentation."[9] The condition can also be difficult to diagnose, especially since many of the numerous symptoms are non-specific in nature. Mast cell activation was assigned an ICD 10 code (D89.40, along with subtype codes D89.41-43 and D89.49) in October 2016.

"Although different diagnostic criteria are published, a commonly used strategy to diagnose patients is to use all three of the following:
  1. Symptoms consistent with chronic/recurrent mast cell release:
    Recurrent abdominal pain, diarrhea, flushing, itching, nasal congestion, coughing, chest tightness, wheezing, lightheadedness (usually a combination of some of these symptoms is present)
  2. Laboratory evidence of mast cell mediator (elevated serum tryptase, N-methyl histamine, prostaglandin D2 or 11-beta- prostaglandin F2 alpha, leukotriene E4 and others)
  3. Improvement in symptoms with the use of medications that block or treat elevations in these mediators"[4]

The World Health Organization has not published diagnostic criteria.

Treatment

Common pharmacological treatments include:

Prognosis

The prognosis of MCAS is uncertain because of lack of studies. [13]

Epidemiology

MCAS is a relatively new diagnosis, being unnamed until 2007, and is believed to be under-diagnosed.

History

The condition was hypothesized by the pharmacologists John Oates and Jack Roberts of Vanderbilt University in 1991, and following a build-up of evidence featured in papers by Sonneck et al.[14] and Akin et al.,[15] finally named in 2007.[7]

Diagnostic criteria were proposed in 2010.[2]

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See also

References
  1. Valent P (2013). "Mast Cell Activation Syndromes: Definition and Classification". Allergy. 68 (4): 417–24. doi:10.1111/all.12126. PMID 23409940.
  2. Akin C, Valent P, Metcalfe DD (2010). "Mast cell activation syndrome: Proposed diagnostic criteria". J. Allergy Clin. Immunol. 126 (6): 1099–104.e4. doi:10.1016/j.jaci.2010.08.035. PMC 3753019. PMID 21035176.
  3. Akin C (2015). "Mast Cell Activation Syndromes Presenting as Anaphylaxis". Immunology and Allergy Clinics of North America. 35 (2): 277–85. doi:10.1016/j.iac.2015.01.010. PMID 25841551.
  4. White, Andrew, Dr. "A Tale of Two Syndromes – POTS and MCAS". The Dysautonomia Dispatch. Dysautonomia International, 17 Feb. 2015. Web. 12 Oct. 2015, at dysautonomiainternational.org.
  5. "About MCAS | Mast Cell Action". www.mastcellaction.org. Retrieved 2020-03-26.
  6. Akin, Cem (August 2017). "Mast cell activation syndromes". Journal of Allergy and Clinical Immunology. 140 (2): 349–355. doi:10.1016/j.jaci.2017.06.007. PMID 28780942.
  7. Afrin, Lawrence B. "A Concise, Practical Guide to Diagnostic Assessment for Mast Cell Activation Disease." WJH World Journal of Hematology 3.1 (2014): 155-232. Archived 2018-08-18 at the Wayback Machine Accessed 29 January 2018
  8. Frieri M (2018). "Mast Cell Activation Syndrome". Clin Rev Allergy Immunol. 54 (3): 353–365. doi:10.1007/s12016-015-8487-6. PMID 25944644.
  9. "Afrin, Lawrence, Dr. "Presentation, Diagnosis, and Management of Mast Cell Activation Syndrome." Mast Cells: Phenotypic Features, Biological Functions and Role in Immunity. Nova Science, 2013. 155-232". Archived from the original on 2018-08-18. Retrieved 2015-10-13.
  10. Milner, Joshua, Dr. "Research Update: POTS, EDS, MCAS Genetics." 2015 Dysautonomia International Conference & CME. Washington DC. Dysautonomia International Research Update: POTS, EDS, MCAS Genetics. Web, at vimeo.com
  11. Finn DF, Walsh JJ (2013). "Twenty-first century mast cell stabilizers". Br. J. Pharmacol. 170 (1): 23–37. doi:10.1111/bph.12138. PMC 3764846. PMID 23441583. A diverse range of mast cell stabilizing compounds have been identified in the last decade from; natural, biological and synthetic sources to drugs already in clinical uses for other indications. Although in many cases, the precise mode of action of these molecules is unclear, all of these substances have demonstrated mast cell stabilization activity and therefore may have potential therapeutic use in the treatment of allergic and related diseases where mast cells are intrinsically involved.Table 1: Naturally occurring mast cell stabilizers
  12. Weng Z, Zhang B, Asadi S, Sismanopoulos N, Butcher A, Fu X, Katsarou-Katsari A, Antoniou C, Theoharides TC (2012). "Quercetin is more effective than cromolyn in blocking human mast cell cytokine release and inhibits contact dermatitis and photosensitivity in humans". PLOS ONE. 7 (3): e33805. Bibcode:2012PLoSO...733805W. doi:10.1371/journal.pone.0033805. PMC 3314669. PMID 22470478.
  13. Weiler, Catherine R.; Austen, K. Frank; Akin, Cem; Barkoff, Marla S.; Bernstein, Jonathan A.; Bonadonna, Patrizia; Butterfield, Joseph H.; Carter, Melody; Fox, Charity C.; Maitland, Anne; Pongdee, Thanai; Mustafa, S. Shahzad; Ravi, Anupama; Tobin, Mary C.; Vliagoftis, Harissios; Schwartz, Lawrence B. (1 October 2019). "AAAAI Mast Cell Disorders Committee Work Group Report: Mast cell activation syndrome (MCAS) diagnosis and management". Journal of Allergy and Clinical Immunology. 144 (4): 883–896. doi:10.1016/j.jaci.2019.08.023. ISSN 0091-6749. PMID 31476322. Retrieved 27 April 2020.
  14. Sonneck K, Florian S, Müllauer L, Wimazal F, Födinger M, Sperr WR, Valent P (2007). "Diagnostic and subdiagnostic accumulation of mast cells in the bone marrow of patients with anaphylaxis: Monoclonal mast cell activation syndrome". Int Arch Allergy Immunol. 142 (2): 158–64. doi:10.1159/000096442. PMID 17057414.CS1 maint: multiple names: authors list (link)
  15. Akin C, Scott LM, Kocabas CN, Kushnir-Sukhov N, Brittain E, Noel P, Metcalfe DD (2007). "Demonstration of an aberrant mast-cell population with clonal markers in a subset of patients with "idiopathic" anaphylaxis". Blood. 110 (7): 2331–3. doi:10.1182/blood-2006-06-028100. PMC 1988935. PMID 17638853.CS1 maint: multiple names: authors list (link)

Further reading
Classification
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