Mastocytosis is a disorder of excessive mast cell proliferation, which is now classified as a myeloproliferative neoplasm. Two clinical entities fall under the mastocytosis umbrella: cutaneous (urticaria pigmentosa) and systemic mastocytosis (with or without cutaneous manifestations). The article deals primarily with the latter.
There is considerable heterogeneity in the presentation of mastocytosis, and in the rate of disease progression. Clinical features include:
- cutaneous manifestations
- hypotension and syncope
- abdominal pain
- nausea, vomiting and diarrhoea
- bone pain and pathological fractures
- associated haematological disorders 7
Mast cells are bone marrow-derived cells that are widely distributed in tissues. They store various biologically active mediators, such as heparin and histamine. Mediator release from mast cells has a central role in the development of type 1 hypersensitivity 1.
In systemic mastocytosis, abnormal proliferation and microscopic infiltration of mast cells involve the skin, bone marrow, gastrointestinal tract, liver and spleen. It is thought that the effects of mastocytosis relate at least in part to mediator release 7.
Imaging findings are best categorised by the system rather than by modality. Most features are relatively non-specific but may suggest the diagnosis in the correct clinical setting.
Bone involvement in mastocytosis can be either lytic, sclerotic or mixed 4,5. Diffuse involvement tends to be more common 11. Usually, the radiographic appearance is that of sclerosis involving primarily the axial skeleton and the ends of the long bones. In some patients, there is generalised osteoporosis with the risk of pathological fractures.
- peptic ulcer disease
- diffuse small bowel thickening
- omental and mesenteric thickening 9
- pulmonary nodules (rare) 2,8
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