MASTOCYTOSIS - REACTIVE OR NEOPLASTIC

Mast cells are now known to derive from CD34(+) haemopoietic stem cell s in the bone marrow. However, it has not yet been established whether the various types of mastocytosis, which involve tumour-like prolifer ation of mast cells, are true neoplastic disorders or reactive/hyperpl astic conditions. In this study tissue specimens (five bone marrow, tw o spleen, one skin) from female patients with histologically confirmed mastocytosis were investigated with a recently developed polymerase c hain reaction assay for the determination of clonality of female cells using the human androgen receptor gene (HUMARA). Mast cells purified to near homogeneity from hysterectomy specimens served as a control. T he findings in bone marrow and skin either were not reproducible, or i ndicated polyclonality. How both ever, both spleen specimens exhibited monoclonality. In addition, DNA analysis by flow cytometry was perfor med and revealed a diploid chromosome content with proliferation indic es of under 8% in all the specimens. This is the first molecular biolo gical study to indicate that mastocytosis is indeed neoplastic in natu re.