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reactive mastocytosisA focal increase in mast cells due to immediate or delayed hypersensitivity reactions, which may also occur in lymph nodes draining benign (e.g., localised mastocytosis, which may be cutaneous or extracutaneous) and urticaria pigmentosa or malignant lesions—e.g., chronic liver or renal disease, leukaemia, lymphoproliferative disorders or Hodgkin lymphoma.
mastocytosisA heterogeneous group of uncommon, poorly understood lesions characterized by ↑ mast cells in one or more tissues or organs, especially skin; mastocytosis may be classified according to extent and behavior. See Mast cell leukemia. Urticaria pigmentosa
• Focal: Single skin lesion: mast cell 'nevus'
• Generalized: Urticaria pigmentosa
Mast cell leukemia
Mast cell sarcoma
Pathogenesis Some cases may be reactive to ↑ soluble mast cell growth factor–kit-ligand, possibly due to an ↑ in proteolytic processing, a cytokine that causes mast cell accumulation, melanocyte proliferation and ↑ melanin production NEJM 1993; 328:1302oa Reactive mastocytosis A focal ↑ in mast cells due to immediate or delayed hypersensitivity reactions, which may also occur in lymph nodes draining benign or malignant lesions, eg chronic liver or renal disease, leukemia, lymphoproliferative disorders or Hodgkin's disease; benign mast cell diseases include localized mastocytosis, which may be cutaneous or extracutaneous and urticaria pigmentosa Systemic mastocytosis A potentially aggressive condition characterized by mast cell proliferation in the skin, liver, lymph nodes, BM, GI tract Clinical Histamine hyperproduction with flushing, vertigo, palpitations, pruritus, colic, dyspnea, nausea; Sx range from mild and intermittent, to severe, disabling, and progressive 'Malignant' systemic mastocytosis A form of mast cell disease that is fatal within 2 years of conversion to an aggressive form