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Mastocytosis

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Mastocytosis, Cutaneous Mastocytosis, Systemic Mastocytosis, Urticaria Pigmentosa

  • See Also
  1. Mast Cell
  • Definitions
  1. Mastocytosis
    1. Abnormal proliferation and accumulation of Mast Cells within various organ systems
    2. May be limited to skin Mast Cell accumulation (Cutaneous Mastocytosis)
    3. May be diffusely increased in Bone Marrow, Spleen, and liver (Systemic Mastocytosis)
  • Pathophysiology
  1. Abnormal proliferation and accumulation of Mast Cells within various organ systems
  2. High number of Mast Cells degranulate, releasing vasoactive agents (esp. Histamine)
  • Types
  1. Cutaneous Mastocytosis
    1. Isolated skin Mast Cell accumulation
    2. Most cases are in children (80% of cases are age <1 year old)
  2. Systemic Mastocytosis
    1. Diffusely increased Mast Cells in Bone Marrow, Spleen, and liver
    2. Most cases are in adults (95% of adult cases)
  • Causes
  • Triggers for Mast Cell Degranulation
  1. Medications (e.g. Opioids, NSAIDs, iodinated contrast, Vancomycin, general Anesthesia)
  2. Physical stimuli (e.g. Exercise, extremes of Temperature, emotional stress)
  3. Surgical procedures
  4. Bites and Stings (e.g. Insect Bites, Animal Bites)
  • Findings
  • Cutaneous Mastocytosis
  1. Pruritus
  2. Urticaria Pigmentosa
    1. Red-Brown Macules or Papules
  • Findings
  • Systemic Mastocytosis
  1. Flushing
  2. Pruritus
  3. Nausea
  4. Vomiting
  5. Abdominal Pain
  6. Anaphylaxis (uncommon, severe cases)
  • Labs
  1. Complete Blood Count
    1. Anemia -mild to moderate (50% of cases)
    2. Eosinophilia (25% of cases)
    3. Monocytosis (50% of advanced cases)
  2. Mastocytosis specific lab markers
    1. Serum Tryptase >20 ng/ml (systemic mastocytocytosis)
    2. Urine 24 hour collection for Histamine or Histamine Metabolites
  3. Skin Biopsy of Urticaria Pigmentosa
    1. Mast Cell aggregation
  4. Bone Marrow Biopsy
    1. Spindle-shaped Mast Cells
    2. Distribution in perivascular, peritrabecular and intertrabecular areas
  5. Other advanced testing
    1. KIT Gene Mutation Analysis
  • Management
  1. Symptomatic Management
    1. Antihistamines for Pruritus
    2. Aspirin for Flushing (adults)
  2. Urticaria Pigmentosa
    1. PUVA
    2. Corticosteroids (severe cases)
  3. Gastrointestinal Symptoms
    1. Mast Cell Stabilizers (e.g. Disodium Chromoglycate)
    2. Proton Pump Inhibitors or H2 Blockers (e.g. Pepcid)
  • References
  1. Castells and Akin in Saini (2017) Mastocytosis Evaluation and Diagnosis, UpToDate, accessed 10/5/2020
  2. Mahmoudi (2014) Immunology Made Ridiculously Simple, MedMaster, Miami, FL, p. 30-1