Mastocytosis and co-existent non-Hodgkin's lymphoma and myeloproliferative disorders.

Generalised mastocytosis is a rare condition characterised by the clinical features of the release of vasoactive peptides from tissue mast cells infiltrating in the reticuloendothelial tissues. The mast cell however appears to have its origin in the pluripotential bone marrow stem cell committed to a basophil and it is therefore not surprising that myeloproliferative and myelodysplastic disorders commonly co-exist or terminate the clinical phase of mastocytosis. Both abnormal proliferation and maturation of the myeloid committed cells are found. Non-Hodgkin's lymphoma can occur before and after mastocytosis becomes manifest. While this is statistically a random event the relationship between lymphokines and mast cell differentiation and proliferation raises the possibility of a benign reactive lymphoid event eventually becoming malignant.