Treatment for Acute Mastocytosis
Start immediately with H1 antihistamines (cetirizine, diphenhydramine, or hydroxyzine) as first-line therapy, add H2 antihistamines (famotidine or ranitidine) if gastrointestinal symptoms persist, and ensure an epinephrine autoinjector is prescribed for emergency use during severe reactions. 1
Immediate Management Algorithm
First-Line Therapy: H1 Antihistamines
- Begin with H1 antihistamines to control itching, flushing, skin rashes, and rapid heartbeat—effective options include diphenhydramine, hydroxyzine, and cetirizine 1
- Doses may need to be 2-4 times higher than FDA-approved levels for adequate symptom control, but monitor carefully as high doses can cause cardiotoxicity 1
Second-Line: Add H2 Antihistamines
- Add H2 antihistamines such as famotidine or ranitidine if gastrointestinal symptoms persist despite H1 antihistamines alone 1
- Combined H1 and H2 therapy is particularly effective for controlling severe pruritus and wheal formation when monotherapy fails 1, 2
Emergency Management Protocol
Acute Mast Cell Activation Attacks
- Administer epinephrine intramuscularly in a recumbent (supine) position immediately for hypotension, wheezing, laryngeal edema, cyanotic episodes, or recurrent anaphylactic attacks 1, 2
- Every patient with mastocytosis must have an epinephrine autoinjector prescribed and caregivers trained in its use 1
Critical Trigger Avoidance
Temperature Control
- Identify and avoid triggers, particularly hot temperatures (and to a lesser extent, cold temperatures), as mast cells are activated by temperature extremes 1
- Rational use of baths, showers, swimming pools, and air conditioning can decrease symptoms and reduce the need for antihistamines 1, 2
Stress and Pain Management
- Avoid anxiety and stress, as they trigger mast cell activation 1
- Control pain carefully—if opioids are needed, safer options include fentanyl and remifentanil 1
Baseline Monitoring Requirements
- Record the type and extent of skin lesions and measure baseline serum tryptase levels before starting therapy 2
- Tryptase levels >20 μg/L indicate increased mast cell burden and/or extensive degranulation, requiring close observation, thorough evaluation, and sometimes hospitalization 2
Important Caveats
Cytoreductive Therapy
- Cytoreductive therapy is strongly discouraged in pediatric and indolent mastocytosis, except in rare cases of aggressive variants with life-threatening risk, due to the benign nature and high rate of spontaneous regression 2
- Reserve cytoreductive therapies (interferon-alpha, cladribine) for aggressive mastocytosis, mast cell leukemia, or treatment-refractory cases 3, 4
Patient and Caregiver Education
- Educate parents, caregivers, pediatricians, teachers, school nurses, and daycare workers about the diagnosis, treatment, and potential risks including infections, vaccinations, dental work, imaging procedures, and surgery 1, 2
- Clarify that cutaneous mastocytosis is not contagious 2