[Mastocyte osteoporosis].

We present five cases of severe osteoporosis accompanied by a skin and/or bone mastocytosis. The rarity of mastocytosis demonstrates that these cases are not the result of simple coincidence, especially since none of them involves other general of phospho-calcium anomalies that could explain the demineralization. The latter is accompanied by a high level of histaminemia or histaminuria, a non-specific anomaly. Mastocyte osteoporosis involves a great many unknown factors on the physiopathological level, but in practice it is necessary to look for a mastocytosis when confronted with a severe osteoporosis that appears to be primary. Cytostatic treatment (chlorambucil, cyclophosphamide) seems capable of improving the evolution of the bone disease.