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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 Provider Primer Series: Mast cell activation syndrome (MCAS)

Mast cell activation syndrome (MCAS), also called mast cell activation disorder (MCAD), is an immunologic condition in which mast cells are aberrantly activated, resulting in inappropriate mediator release.


  • MCAS can be responsible for chronic symptoms in multiple organs that cannot be attributed to another cause[vi].
  • Patients frequently receive diagnosis for a number of idiopathic conditions prior to correct diagnosis with MCAS[vi].
  • Mast cell activation syndrome is overwhelmingly a secondary condition. MCAS can be secondary to a number of conditions, including autoimmune diseases, connective tissue diseases, and atopic conditions[i].
  • The term “primary MCAS” refers to mediator release symptoms associated with mastocytosis[xvii] . However, the term “mastocytosis” generally conveys the understanding that both proliferation and mediator release symptoms are possible.
  • In idiopathic MCAS, no cause for symptoms can be identified[xvii] .
  • The presence of multiple mast cell patients in one family is not uncommon. A heritable gene has not yet been identified. Epigenetic mechanisms are suspected for transmission of mast cell disease to another generation[iv].
  • Approximately 75% of mast cell patients have at least one first degree relative with mast cell disease and not always the same subtype[ii]. For example, a mother may have MCAS, while one of her children has SM and the other has CM.

Diagnostic criteria

  • MCAS is a recently described diagnosis. In the absence of large studies, several groups have developed their own, sometimes conflicting, diagnostic criteria.
  • Differential diagnoses with potential to cause similar symptoms should be considered and excluded[iii].
  • The criteria most frequently used include those by a 2010 paper by Akin, Valent and Metcalfe[iii]; a 2011 paper by Molderings, Afrin and colleagues[iv]; and a 2013 paper by Castells and colleagues[v].
  • The criteria described in the 2011 paper by Molderings, Afrin and colleagues have been updated to include response to medication[vi].
  • Of note, a 2012 consensus proposal[x] was authored by a number of mast cell experts including Valent, Escribano, Castells, Akin and Metcalfe. It sees little practical use and is not generally accepted in the community.
  • The major sets of criteria listed above all include the following features:
    • Recurrent or chronic symptoms of mast cell activation
    • Objective evidence of excessive mast cell mediator release
    • Positive response to medications that inhibit action of mast cell mediators
  • Valent warns that in some cases, patients may not fulfill all criteria but still warrant treatment: “In many cases, only two or even one of these three criteria can be documented. In the case of typical symptoms, the provisional diagnosis of ‘possibly MCA/MCAS’ can be established, and in acute cases, immediate treatment should be introduced.”[vii]

Evidence of mediator release

  • Mast cells produce a multitude of mediators including tryptase, histamine, prostaglandin D2, leukotrienes C4, D4 and E4, heparin and chromogranin A[viii].
  • Serum tryptase and 24 hour urine testing for n-methylhistamine, prostaglandin D2, prostaglandin 9a,11b-F2 are frequently included in testing guidelines in literature (Castells 2013)[ix], (Akin 2010)[x], (Valent 2012)[xi].
  • It can be helpful to test for other mast cell mediators including 24 hour urine testing for leukotriene E4[xii]; plasma heparin[xiii]; and serum chromogranin A[xiv].
  • In most instances, elevation of a mediator must be present on two occasions[ix]. This helps to exclude situations of appropriate mast cell activation, such as infection or wound healing.
  • For patients with baseline tryptase level >15 ng/mL, elevation of tryptase above this baseline is only required on one occasion[viii].

Symptoms associated with mast cell activation

  • Mediator release causes a wide array of symptoms, including hypertension[xv], hypotension, hypertension, wheezing, itching, flushing, tachycardia, nausea, vomiting, diarrhea, constipation, headache, angioedema, fatigue, and neurologic symptoms[iv].
  • In a small MCAS cohort (18 patients), 17% had a history of anaphylaxis[xvii] . A larger data set is desirable.
  • Patients with history of anaphylaxis should be prescribed epinephrine autoinjectors[v]. If patient must be on a beta blocker, they should be prescribed a glucagon injector for use in the event of anaphylaxis[v].

Response to medications that inhibit action of mast cell mediators

  • Treatment of MCAS is complex and may require a number of medications. Second generation H1 antihistamines; H2 antihistamines; and mast cell stabilizers are mainstays of treatment[xvi].
  • Additional options include aspirin; anti-IgE; leukotriene blocker; and corticosteroids[xiii] .
  • First generation H1 antihistamines may be used for breakthrough symptoms[xiii] .
  • “An important point is that many different mediators may be involved in MCA-related symptoms so that the final conclusion the patient is not responding to antimediator therapy should only be drawn after having applied several different antimediator-type drugs[xiii] .
  • Inactive ingredients are often to blame for reaction to mast cell mediator focused medications. Many mast cell patients see benefit from having medications compounded[xvii].

Natural history

  • In one MCAS cohort of 18 patients, 33% had a complete (no unmanaged symptoms) response and 33% had a major (only one serious symptom) response after one year of mast cell treatment[xviii].
  • In another MCAS cohort of 135 patients, 51% demonstrated significant improvement, 11% had no obvious change in symptom severity and 38% experienced worsening symptoms[v]. (Author’s note: While described in an Afrin 2016[v] paper, the data from this cohort has not yet been published. Molderings is the principle investigator.



[i] Frieri M, et al. (2013). Mast cell activation syndrome: a review. Current Allergy and Asthma Reports, 13(1), 27-32.

[ii] Molderings GJ, et al. (2013). Familial occurrence of systemic mast cell activation disease. PLoS One, 8, e76241-24098785

[iii] Akin C, et al. (2010). Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol, 126(6), 1099-1104.e4

[iv] Molderings GJ, et al. (2011). Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology, 4(10), 10.1186/1756-8722-4-10

[v] Castells M, et al. (2013). Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Clin Ther, 35(5), 548-562.

[vi] Afrin LB, et al. (2016). Often seen, rarely recognized: mast cell activation disease – a guide to diagnosis and therapeutic options. Annals of Medicine, 48(3).

[vii] Valent P. (2013). Mast cell activation syndromes: definition and classification. European Journal of Allergy and Clinical Immunology, 68(4), 417-424.

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

[ix] Picard M, et al. (2013). Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Clinical Therapeutics, 35(5), 548-562.

[x] Akin C, et al. (2010). Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol, 126(6), 1099-1104.e4

[xi] Valent P, et al. (2012). Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol, 157(3), 215-225.

[xii] Lueke AJ, et al. (2016). Analytical and clinical validation of an LC-MS/MS method for urine leukotriene E4: a marker of systemic mastocytosis. Clin Biochem, 49(13-14), 979-982.

[xiii] Vysniauskaite M, et al. (2015). Determination of plasma heparin level improves identification of systemic mast cell activation disease. PLoS One, 10(4), e0124912

[xiv] Zenker N, Afrin LB. (2015). Utilities of various mast cell mediators in diagnosing mast cell activation syndrome. Blood, 126(5174).

[xv] Shibao C, et al. (2005). Hyperadrenergic postural tachycardia syndrome in mast cell activation disorders. Hypertension, 45(3), 385-390.

[xvi] Cardet JC, et al. (2013). Immunology and clinical manifestations of non-clonal mast cell activation syndrome. Curr Allergy Asthma Rep, 13(1), 10-18.

[xvii] Afrin LB. “Presentation, diagnosis and management of mast cell activation syndrome.” In: Mast Cells. Edited by David B. Murray, Nova cience Publishers, Inc., 2013, 155-232.

[xviii] Hamilton MJ, et al. (2011). Mast cell activation syndrome: a newly recognized disorder with systemic clinical manifestations. Journal of Allergy and Clinical Immunology, 128(1), 147-152.e2

Progression of mast cell diseases (Part 5)

What is the typical age of onset for children with mastocytosis?

“Mastocytosis [cutaneous, in children]… 55% of cases presenting from birth to 2 years of age, 10% in children younger than 15 years old, and 35% in those over the age of 15. There has, however, been no gender bias noted in the cases of pediatric mastocytosis.” (Frieri 2013)


Do symptoms outside of the skin mean my child has systemic, not cutaneous, mastocytosis?

“Systemic symptoms are typically a result of mast-cell mediator release but do not prove systemic mast-cell hyperplasia [overproliferation].” (Frieri 2013)

“Clinical presentation was evaluated in an earlier study conducted by the National Institutes of Health (NIH) in which 83% of the children presented with pruritis, 65% with flushing, 53% with vesicles, 41% with abdominal pain, 18% with bone pain, and least commonly 12% with headache.” (Frieri 2013)

“Systemic mastocytosis in children is extremely rare.” (Frieri 2013)


What do studies say about kids growing out of mastocytosis?

“Pediatric mastocytosis is generally a benign disease that is transient in nature, as there is generally a spontaneous regression of the condition by puberty.” (Frieri 2013)

“There was complete regression of disease as defined by cutaneous findings and symptoms (clinical disease severity) in 10 of 15 patients (67%). Three patients had major (20%) and two had partial regression of disease (13%). Repeat marrow examinations on three patients with persistent disease documented systemic mastocytosis based on marrow findings in one patient who had partial regression of disease and was the only patient with initial [] evidence of systemic disease. Of the remaining two patients, one demonstrated partial regression and the other major regression of disease; and neither had evidence of systemic mastocytosis.” (Frieri 2013)

“10 of 15 of patients had complete resolution of cutaneous disease and symptoms at follow-up approximately 20 years later. This resolution of disease, based on cutaneous findings and symptom scores, occurred in the absence of use of topical or systemic steroids, PUVA or cytoreductive agents including imatinib… the natural history of disease is improvement.” (Uzzaman 2009)

“In one [] pediatric report where records and follow-up examinations were available for 25 children with UP, and an average follow-up was approximately 5 years, 76 % improved, 16 % remained unchanged, one had complete disease resolution, and one was worse.” (Uzzaman 2009)

“In a second [] study, 55 children with UP were followed for at least two years after initial examination, during which time 9% had involution of all lesions. In this study, where the average follow-up was 4.1 years, 36% had shown improvement over 6.1 years, and in 55% disease remained unchanged.” (Uzzaman 2009)

“In a third [] study, records of mastocytosis patients [] were available to assess disease outcome over a 1–15 year period. Thirty-five of 62 patients with UP (56%) showed complete disease resolution.” (Uzzaman 2009)

“In a fourth [] study, of 72 cases of UP, 20% cleared disease over an average of 13 years, while 50% improved, 18% were no different, and 10% were worse.” (Uzzaman 2009)

“The age of inception of pediatric-onset cutaneous mastocytosis has been reported to have prognostic implications. In previous studies, skin lesions characterized as hyperpigmented red brown macules or papules typically were reported to appear prior to two years of age. In five such studies with 180, 112, 71, 55 and 17 patients, disease-onset prior to age 2 years was seen in 78, 92, 98, 92, and 82%, respectively. In the majority of patients, these lesions were reported to fade or resolve by late adolescence or early adulthood. Fading or resolution of UP is also reported in some adults (around 20%), although bone marrow disease persisted.” (Uzzaman 2009)


How do biopsies of children with mastocytosis differ from adults with mastocytosis?

“In order to analyze the extent of mast-cell hyperplasia, [] bone-marrow biopsies were performed and analyzed. In one study, it was found that in 10 of 17 children with mastocytosis, there were focal areas of mast-cell hyperplasia, which had [] aggregates of mast cells, eosinophils, and early myeloid cells.(Frieri 2013)

“Another study found that the bone-marrow lesions of children had small, [] clusters of mast cells with round and oval nuclei rather than spindle-shaped mast cells, as found in adult bone-marrow lesions.” (Frieri 2013)

“Overall when quantifying mast-cell hyperplasia, there was a higher load of mast cells in children with mastocytosis than in adults with mastocytosis.” (Frieri 2013)

“[T]he difference in presentation between adult and pediatric cases of mastocytosis may result from the difference not only in the mast-cell load but also the distribution of where the mast cells are most likely to be found.” (Frieri 2013)


Do increased mast cells in the bone marrow mean my child will not grow out of their disease?

“Five patients had increased mast cells and three patients had spindle shaped mast cells on the initial bone marrow biopsy. One of these patients had complete resolution of clinical and constitutional symptoms at follow-up. Three of the remaining four patients were re-evaluated. One of these was the patient with continued systemic disease, one had persistent DCM and one had continued UP. However, two other patients with continued UP had neither an increase in mast cells nor spindle shaped mast cells noted on original bone marrow examination. Thus, while the presence of increased mast cells and of spindle-shaped mast cells was more often observed in those with persistent disease, the association was not sufficient to predict outcome.” (Uzzaman 2009)


Are children with mastocytosis CKIT+?

“Earlier studies by Verzijl found that 25% of pediatric patients with UP had an activating D816V mutation present. Another Longley study found that 36% of pediatric patients had another mutation at codon 816. (This is where the D816V mutation is found.)…One study found that 25% of pediatric patients with the UP form of mastocytosis had a D816V mutation. It was also found that 10 out of 12 patients had another [non-D816V] mutation at the location.” (Frieri 2013)

“A later study by Bodemer in 50 pediatric patients with ages ranging from birth to 16 years found 86% of them had a c-KIT mutation, with 36% being a D816V point mutation, 2 out of 50 cases being a D816Y mutation, and one case being a D816I mutation. There were also 29 of 50 patients with [no mutation] at the 816 codon.” (Frieri 2013)

“44% of the patients were found to have a mutation outside of c-KIT with the mutations lying in exons 8, 9, and 11. There was also a subset of 28% of the patients with a M541L mutation at exon 10. [T]he patients with a M541L mutation had [no mutation] at codon 816. When the blood sample of 13 patients was analyzed, it was found that there was no c-KIT mutation, which suggests that the mutation is somatic rather than germline, meaning that this mutation is not inherited from a patient’s parents.” (Frieri 2013)


Do mastocytosis children generally have problems with anesthesia?

Note: always follow appropriate premedication protocols for mast cell patients and work with managing physician.

“Twenty-two patients with pediatric mastocytosis, with a median age of 3.2 years (range 6 months to 20 years) at the time of the procedure, were anesthetized for 29 diagnostic and surgical procedures. All variants of the disease are represented in this series. Most patients had a history of flushing, pruritus, gastroesophageal refux disease (GERD), and abdominal pain; one patient had history of spontaneous anaphylaxis. Routine anesthetic techniques were used, and despite the complexity of the disease, the perioperative courses were uncomplicated and without serious adverse events.” (Frieri 2013)


Note: These quotes are all drawn from two papers which extensively referenced previous publications. I ran down the articles referenced, but felt that these two reviews gave excellent summaries, and so I quoted them exclusively.



Frieri, Marianne, et al. Pediatric mastocytosis: A review of the literature. Pediatr Allergy Immunol Pulmonol. Dec 1, 2013; 26(4): 175-180.

Uzzaman, Ashraf, et al. Pediatric-onset Mastocytosis: A long term clinical follow-up and correlation with bone marrow histopathology. Pediatr Blood Cancer. Oct 2009; 53 (4): 629-634.

Kettelhut BV., Metcalfe DD. Mastocytosis. J Invest Dermatol 1991; 96:115S–118S.

Lange M., Bogusław Nedoszytko B., Górska A., Żawrocki A., Sobjanek M., Kozłowski D. Mastocytosis in children and adults: clinical disease heterogeneity. Arch Med Sci 2012; 8:533–541.

Bodemer C., Hermine O., Palmérini F., Yang Y., Grandpeix-Guyodo C., Leventhal PS., Hadj-Rabia S., Nasca L., Georgin-Lavialle S., Cohen-Akenine A., Launay JM., Barete S., Feger F., Arock M., Catteau B., Sans B., Stalder JF., Skowron F., Thomas L., Lorette G.Plantin P, Bordigoni P, Lortholary O, de Prost Y, Moussy A, Sobol H, Dubreuil P. Pediatric mastocytosis is a colonal disease associated with D816V and other activating C-KIT mutations. J Invest Dermatol 2010; 130:804–815.


Progression of mast cell diseases: Part 1

Among mast cell patients, we generally assume that a designation of SM means indolent systemic mastocytosis (ISM.) However, in research papers, this term can mean ISM, SSM, ASM or MCL. Advanced SM usually means ASM or MCL. These terms generate a lot of confusion in the patient population. When reading a paper, abbreviations are usually defined on the first page or within the introduction. It is important to check on what the researchers are using the term SM for.

As an example, let’s look at this really alarming quote to someone who thinks SM means ISM:

“The life expectancy of SM patients was shorter relative to age- and sex-matched controls. As initially observed by Travis et al, survival decreased rapidly after diagnosis: to 60% at 3 years, with a subsequent slower decline to 50% at 5 years. Beyond 5 years, the slope of the survival curve was similar to that of the control population. This observation confirms that the deaths in SM patients within the first 3 (and up to 5) years after diagnosis.” (Lim 2009)

In this paper, SM meant ISM, SM-AHNMD, SSM, ASM and MCL. When you average those survival rates together, you get a sharp decline in survival for the first five years. After that, it returns to normal, because most of the ASM and MCL patients in that study died by that time.


I get asked A LOT about whether or not ISM is progressive. I see a lot of people describe it as progressive. In medicine, progression usually means moving from one diagnostic category to a more serious one (like ISM to SSM.) However, a lot of patients use this term to mean a worsening of symptoms or disability while staying in the same diagnostic category (like ISM with mild daily symptoms to ISM with severe daily symptoms). Those are two different things. I’m going to answer both.


What is the life expectancy with ISM?

It’s normal.

“Patients with ISM have a favorable prognosis. These patients may suffer from mediator-release symptoms, but do not suffer from significant organopathy caused by MC infiltration.” (Valent, 2003)

In a study of 159 patients, 2.2% ± 1.3% died within five years of diagnosis, and 11% ± 5.9% died within twenty five years of diagnosis. “The majority of deaths in this ISM cohort were unrelated to mastocytosis.” (Pardanini 2013)

In a study of 342 patients, ISM was the largest subgroup with 159 patients.  They were significantly younger at presentation (median age 49 years.) “Overall median survival was not significantly different than that of the age and gender matched control population. Advanced age was the primary determinant of inferior survival.” (Pardanini 2013)


Will my ISM symptoms get worse with time?

There is really no way to know. In some people, they are stable, while in others, they fluctuate. However, mediator release symptoms (degranulation symptoms) are known to be more common in ISM than ASM and MCL.

“ISM patients can be highly symptomatic; in one study, 70% reported at least some degree of functional limitation, of which 17% reported severe limitation.” (Pardanini 2013)

“The type and severity of symptoms were independent of disease classification (CM vs SM), KITD816V status, and serum tryptase level.” (Pardanini 2013)


If my ISM symptoms get worse, does that mean I am progressing to a more severe category, like SSM, ASM or MCL?


“One important aspect in this regard is that mediator-related symptoms per se are not indicative of aggressive mastocytosis unless accompanied by C-findings.” (Valent 2003)

“Moreover, organomegaly per se is not necessarily indicative of aggressive SM.” (Valent 2003)

“In fact, in a group of patients with SM, organomegaly is recorded over many years without impairment of organ function or development of C-findings.” (Valent 2003)

“The type and severity of symptoms were independent of disease classification (CM vs SM), KITD816V status, and serum tryptase level.” (Pardanini 2013)



Pardanini, Animesh. How I treat patients with indolent and smoldering mastocytosis (rare conditions but difficult to manage.) 2013; Blood: 121 (16).

Pardanini, Animesh. Systemic mastocytosis in adults: 2013 update on diagnosis, risk stratification, and management. 2013; American Journal of Hematology: 88 (7).

Pardanini, Animesh. Prognostically relevant breakdown of 123 patients with systemic mastocytosis associated with other myeloid malignancies. 2009; Blood: 114 (18).

Lim, Ken-Hong, et al. Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors. 2009; Blood: 113 (23).

Valent, Peter, et al. How I treat patients with advanced systemic mastocytosis. 2010; Blood: 116 (26).

Matito, Almudena, et al. Serum tryptase monitoring in indolent systemic mastocytosis: association with disease features and patient outcome. 2013; PLOS One.

Sperr, Wolfgang. Diagnosis, progression patterns and prognostication in mastocytosis. 2012; Expert Review of Hematology: 5 (3): 261-274.

Valent, Peter, et al. Aggressive systemic mastocytosis and related mast cell disorders: current treatment options and proposed response criteria. 2003; Leuk Res 27 (7): 635-41.

Hauswirth, Alexander, et al. Response to therapy with interferon alpha-2b and prednisolone in aggressive systemic mastocytosis: report of five cases and review of the literature. 2004; Leuk Res 28 (3): 249-257.