Overview
Definition:
Mastocytosis is a rare group of disorders characterized by the abnormal proliferation and accumulation of mast cells in one or more organs
in children, cutaneous mastocytosis (CM) is most common, typically presenting as urticaria pigmentosa
Systemic mastocytosis (SM) is less frequent but can have more severe manifestations.
Epidemiology:
Cutaneous mastocytosis affects approximately 1 in 10,000 to 1 in 1,000 children, with over 90% presenting before age 2
Systemic mastocytosis is rare in children, accounting for less than 10% of all pediatric mastocytosis cases
Boys are slightly more affected than girls.
Clinical Significance:
While often benign and self-limiting in children (CM), mastocytosis can present with significant morbidity due to mast cell degranulation
Flushing and anaphylaxis are life-threatening emergencies requiring prompt recognition and management, impacting quality of life and posing diagnostic challenges for pediatricians and trainees preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Flushing episodes: Sudden onset of diffuse skin redness, often accompanied by warmth
Associated symptoms: Pruritus, urticaria (hives), gastrointestinal upset (abdominal pain, vomiting, diarrhea), headache, dizziness, palpitations, hypotension (in severe reactions)
Anaphylaxis symptoms: Acute onset of angioedema, bronchospasm (wheezing, dyspnea), cardiovascular compromise (tachycardia, hypotension, syncope), and gastrointestinal symptoms.
Signs:
Cutaneous lesions: Solitary or multiple maculopapular lesions, typically reddish-brown (urticaria pigmentosa), which urticate (swell) and itch when rubbed (Darier's sign)
Systemic signs during degranulation: Tachycardia, hypotension, tachypnea, hypothermia or hyperthermia, pallor or flushing, and wheezing.
Diagnostic Criteria:
Diagnosis of CM is primarily clinical based on the presence of characteristic skin lesions
For SM, WHO criteria involving major and minor criteria are used, often requiring bone marrow biopsy and tryptase levels, though this is less common in pediatric cases unless severe symptoms are present.
Diagnostic Approach
History Taking:
Detailed history of trigger factors for flushing episodes (e.g., insect stings, certain foods, medications, heat, exercise, emotional stress)
Frequency, duration, and severity of flushing
Associated symptoms of systemic involvement (GI, respiratory, cardiovascular)
Family history of atopy or mastocytosis
Prior adverse reactions to medications or insect stings.
Physical Examination:
Thorough skin examination for characteristic lesions of urticaria pigmentosa or other mastocytosis variants
Assessment for systemic involvement: Vital signs (HR, BP, RR, temperature), respiratory auscultation for wheezing, abdominal palpation for organomegaly, examination for signs of angioedema.
Investigations:
Serum tryptase levels: Elevated basal serum tryptase can suggest SM, but levels can also be transiently elevated during degranulation
Specific IgE testing for allergens if suspected
Bone marrow biopsy: Indicated for suspected SM or severe refractory CM, to assess mast cell infiltration.
Differential Diagnosis:
Other causes of flushing: Carcinoid syndrome, pheochromocytoma, menopausal flushing, hyperthyroidism, adverse drug reactions
Other causes of urticaria: Allergic reactions, viral exanthems
Other causes of anaphylaxis: Food allergies, insect sting allergies, medication allergies.
Management
Initial Management:
Immediate cessation of offending trigger if identifiable
For mild flushing: Observation
For severe flushing or suspected anaphylaxis: Ensure airway patency, administer oxygen
Rapid assessment of ABCs (Airway, Breathing, Circulation).
Medical Management:
Anaphylaxis management: Epinephrine (0.01 mg/kg, max 0.3-0.5 mg IM, repeat every 5-15 mins as needed)
Antihistamines (H1 and H2 blockers: e.g., diphenhydramine 1 mg/kg/dose IV/PO, ranitidine 1-2 mg/kg/dose IV/PO)
Corticosteroids (e.g., methylprednisolone 1-2 mg/kg/dose IV)
Bronchodilators (e.g., albuterol nebulized for bronchospasm).
Pharmacological Management:
Long-term management of recurrent flushing or symptoms: H1 antihistamines (e.g., cetirizine, loratadine) for pruritus and urticaria
H2 antihistamines
Cromolyn sodium (oral) to stabilize mast cells
Avoidance of known triggers
For rare cases of symptomatic SM: Interferon-alpha or tyrosine kinase inhibitors (e.g., imatinib) are used in adults, rarely in children.
Supportive Care:
Education of parents/guardians on trigger avoidance and recognition of anaphylaxis symptoms
Provision of an anaphylaxis emergency action plan and auto-injector (e.g., epinephrine auto-injector) if indicated
Close monitoring for recurrent episodes
Nutritional support if gastrointestinal symptoms are significant.
Anaphylaxis Plan Pediatric
Recognition:
Sudden onset of urticaria, angioedema, pruritus, flushing, abdominal pain, vomiting, diarrhea, wheezing, dyspnea, stridor, dizziness, syncope, or hypotension.
Immediate Actions:
Call for emergency medical services (dial 108/112)
Administer epinephrine 0.01 mg/kg (max 0.3 mg for children <30 kg
max 0.5 mg for children >30 kg) intramuscularly into the anterolateral thigh
Position the child supine with legs elevated if hypotensive
if vomiting or respiratory distress, position on their side.
Medications:
Epinephrine (first-line)
Antihistamines (H1 and H2)
Corticosteroids
Oxygen
Bronchodilators if bronchospasm present.
Transport And Monitoring:
Transport to the nearest emergency department via ambulance for continued observation and management
Monitor vital signs, airway, and breathing closely
Continuous ECG monitoring may be necessary.
Follow Up:
Once stable, referral to a pediatric allergist/immunologist for further evaluation, management, and education
Review of the anaphylaxis episode and trigger identification
Prescription of an epinephrine auto-injector and comprehensive action plan for home and school use.
Complications
Early Complications:
Anaphylactic shock leading to hypoperfusion and organ damage
Airway obstruction due to angioedema or bronchospasm
Cardiac arrhythmias
Gastrointestinal bleeding.
Late Complications:
In SM, bone demineralization (osteoporosis), cytopenias, organomegaly (hepatosplenomegaly), and increased risk of infections
Transformation to aggressive mast cell leukemia (extremely rare in children).
Prevention Strategies:
Strict avoidance of identified triggers
Prompt administration of epinephrine during anaphylactic episodes
Long-term prophylactic medications (antihistamines, cromolyn) in select cases
Parental/guardian education and preparedness with auto-injectors.
Key Points
Exam Focus:
DNB/NEET SS exam focus: Recognizing anaphylaxis in a child with mastocytosis
Management algorithms for anaphylaxis
Differentiating CM from SM in pediatric context
Role of tryptase
Triggers for degranulation.
Clinical Pearls:
Always have epinephrine readily available for children with mastocytosis, even if previously asymptomatic
Emphasize trigger avoidance to parents
Urticarial lesions that urticate on rubbing (Darier's sign) are characteristic of CM.
Common Mistakes:
Delaying epinephrine administration in suspected anaphylaxis
Underestimating the severity of mast cell degranulation reactions
Inadequate trigger avoidance education for parents
Misinterpreting transient tryptase elevations.