Mastocitose

💡
Mastocitose: caracterizada por uma aumento patológico do número de mastócitos em vários tecidos: pele, bone marrow, liver, gastrointestinal, spleen, lymph nodes.
 
Heterogenous group
 
Classificação (2008 WHO)
Mastocitose Cutânea | Urticaria pigmentosa
Mastocitose Sistémica
  • Age of onset: child or adult
  • Location of the disease (cutaneous or systemic)
  • Course (indolent or aggressive)
notion image
 
Fisiopatologia
  • Mastócitos
    • Derivcam de Células CD34+ pluripotentes da medula óssea
    • Migram pela corrente sanguínea até aos seus sítios específicos
      • Na pele, estão preferencialmente junto a vasos sanguíneos, nervos, folículos pilosos
    • Maturam por influencia de citoquinas (IL4, NGF)
    • Função
      • Papel sentinela, estimulando o sistema imunitário contra parasitas e bactérias
      • Promovem a reparação e regeneração tecidular
      • Regulam angiogénese, tónus vascular e permeabilidade
    • Ativação
      • Mecanismos imunológicos e não imunológicos (ver urticária)
    • Mediadores libertados
        • notion image
      • Mast cell growth factor SCF also stimulates melanocytes → increased pigmentation
 
Histologia
  • Mastócitos têm grânulos metacromáticos que coram com toluidine azul
  • KIT membranar (CD117) é o marcador imunohistoquímico muitas vezes usado
 
DDx
  • Disorders that cause a secondary increase in mast cells
    • Parasitic infections
      • Toxoplasmosis
    • Allergic reactions (urticaria, insect bites)
    • Immunological reactions (GVHD, granulomatous reactions)
    • Benign tumors (hemangioma, neurofibroma)
    • Benign hematological disorders (thrombocytopenia, hypereosinophilic syndrome, porphyrias, Castleman’s disease)
    • Malignant disorders (Hodgkin’s and other lymphomas)
 
Exames complementares
  • Serum triptase
  • Urinary histamine
 
Tratamento
  • Prognosis for mastocytosis in children is almost always favorable. Pigmented urticaria regresses in half of cases around puberty, while congestive manifestations fade around the age of 2 or 3.
  • There is currently no cure
  • Elimintation of mast cell degranulation factors
    • Avoid: general anesthesia, imaging with iodinated contrast agents, medications
    • Introduction of drugs that may induce degranulation of mastcells must be carried out under strict medical supervision with paramedication with antihistamines
    • General anesthesia without precautions or without information from the anesthesiologist is considered high risk in these patients
  • Symptomatic treatment
    • Antihistamines
    • Proton pump inhibitor if peptic ulcer due to gastric histamine release
    • Disodium cromoglycate - mast cell membrane-stabilizer. 800mg/day for adults, 60-100mg/day for children
    • Phototherapy
      • PUVA, UVA1
    • Topical very strong corticosteroids
    • Adrenaline if signs of anaphylatic shock
    • Biphosphonates for bone pain and osteoporosis
  • If aggressive and/or symptomatic
    • Tyrosine kinase inhibitors
      • Imatinib, masitinib, midostaurin
      • Interferon
      • Chemptherapies
      • Allogenic bone marrow transplant