[Study of mastocytes in 1298 bone biopsies. Relationship between mastocytes and osteoporosis]

The relationship between the bone damage in systemic mastocytosis and reactional mastocytosis is still poorly understood. The purpose of this study was to determine the incidence of excessive mastocytes in a series of bone biopsies and their significance in cases of osteoporosis. The mastocytes were routinely counted in 1,298 successive biopsies stained with May Grumwald Giemsa: 131 biopsies had more than 5 mastocytes/mm2, i.e., 10% of all samples for all diagnoses combined. In 11 patients (13 bone biopsies) with a large excess of mastocytes (more than 15/mm2) and osteoporosis, the biopsies were examined again to look for mastocytic nodules suggesting bone mastocytosis: mastocytic nodules of this type were found in only 4 cases. The mastocyte is an active cell which may play a role in bone metabolism through the intermediary of its mediators. In osteoporosis, the incidence and significance of excessive mastocytes is not yet understood; this excess of mastocytes appears to correspond to reactive mastocytosis rather than systemic mastocytosis.