Histomorphometric study of mast cells in normal bone, osteoporosis and mastocytosis using a new stain.

A new stain for mast cells (Mc) in bone was applied in 9 normal, 14 osteoporotic, and 1 case of systemic mastocytosis. Examination included the following calculations: Mc counts according to various area and perimetry referents including cortical (Ct) and cancellous (Cn) components; proportion of Mc types; and diameter and area of ovoid Mc. The following findings were noted: (1) in all groups, Mc counts were higher in the Ct compared with Cn bone, and Mc counts correlated with type but not size of Mc; (2) in osteoporotics compared with normals, Mc counts were higher in Cn but not Ct bone for both area and perimetry referents; (3) a lower proportion of ovoid Mc were seen in osteoporotics; (4) two cases of osteoporosis had similar Mc counts to a case of mastocytosis, but the latter had a higher proportion of spindle- and bizarre-shaped Mc and a higher proportion of Mc in contact with the bone surface. The Mc by virtue of an increase in number, closer contact with bone surface, and pattern of morphological types may have a role in osteoporosis in occasional instances.