Systemic mastocytosis

Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU

A prevalence of mastocytosis of 1 in 10000 inhabitants has been reported, but underdiagnosis is assumed http://buff.ly/1ntpFM3. Mastocytosis may be the underlying diagnosis in a considerable subset of patients with recurrent “idiopathic anaphylaxis” http://buff.ly/Qj4Nw2.

Pathogenesis

Systemic mastocytosis is characterized by clonal expansion of mast cells, and most patients present with a genetic mutation in the stem cell factor receptor (KIT) gene. KIT or C-kit receptor is also called CD117. KIT is cytokine receptor expressed on the cell surface. KIT receptors binds to stem cell factors which causes certain types of cells to grow.

Some patients present with eosinophilia and symptoms may overlap with the hypereosinophilic syndrome.

Diagnosis

Serum tryptase level differentiate systemic mastocytosis from anaphylaxis. Bone marrow biopys is needed for definitive diagnosis.

Treatment

Treatment options for systemic mastocytosis include:

- H1- and H2-histamine-receptor blockade (e.g., cetirizine and ranitidine)
- oral disodium cromoglycate blocks the release of mediators from mast cells
- leukotriene-receptor blockade (montelukast)
- inhibition of PGD2 generation with acetylsalicylic acid (aspirin)
- proton-pump inhibitor (PPI) (e.g., omeprazole)

Oral cromolyn sodium in the management of systemic mastocytosis

A multicenter, double-blind, placebo-controlled trial of the efficacy of oral cromolyn sodium (200 mg orally four times per day) was conducted in 11 patients with systemic mastocytosis who had been maintained with the drug on an individualized compassionate-need basis. When the symptom scores were analyzed for gastrointestinal manifestations of disease (diarrhea, abdominal pain, nausea, and vomiting), cromolyn sodium treatment was significantly beneficial relative to placebo (p less than 0.02), whereas the benefit for nongastrointestinal manifestations did not reach statistical significance.

Oral cromolyn sodium is FDA-approved for management of systemic mastocytosis.

References

Cromolyn sodium in the management of systemic mastocytosis. Horan RF, Sheffer AL, Austen KF. J Allergy Clin Immunol. 1990 May;85(5):852-5.
http://www.ncbi.nlm.nih.gov/pubmed/2110198
Advances in basic and clinical immunology in 2007. Journal of Allergy and Clinical Immunology - Volume 122, Issue 1 (July 2008).
Neuropeptide blood levels correlate with mast cell load in patients with mastocytosis http://goo.gl/vlQhm
Mastocytosis. NEJM blog, 2011.
Mastocytosis - Where are we now? World Allergy Organization summary, 2012.
Proposed diagnostic algorithm for patients with suspected mastocytosis. Allergy, 2014 http://buff.ly/1hZ4ayz

Systemic mastocytosis - Mayo Clinic video:



Pierre Noel, M.D., hematologist at Mayo Clinic in Arizona, discusses the diagnosis and treatment of systemic mastocytosis or mast cell disease.

Mast Cell Disorders (presentation on Google drive):



Published: 02/12/2009
Updated: 02/03/2012