Mast cell: Originate from same precursor as basophils; contain basophilic granules a rare disorder characterized by abnormal mast cell proliferation and accumulation in tissues.

• Subtypes
  • Cutaneous mastocytosis: limited to skin
  • Systemic mastocytosis: multiorgan involvement (e.g., bone marrow, GI tract) with or without skin manifestations
• Associated with mutations in c-Kit gene and elevated serum tryptase levels
  • Results in high histamine levels, leading to:
    • Pruritus, flushing, abdominal pain, diarrhea, hypotension
    • Gastric ulcers (due to increased gastric acid secretion). See Stomach histology