Interaction Between Sclerostin and Mast Cells in Fibro-Osseous Lesions of the Jaws

To assess the sclerostin, β-catenin, and tryptase expression in fibro-osseous lesions (FOL) of the jaws.

Immunohistochemistry analysis was performed for these proteins on FOL and non-lesional bone. The sclerostin-positive cells were scored from 0 (no expression) to 3 (high expression).

We analyzed 46 FOL biopsies and selected 38 patients. Categorization showed 15 fibrous dysplasia (FD), eight juvenile trabecular ossifying fibroma (JTOF), two psammomatoid ossifying fibroma (PsOF), and 13 FOL. We found more sclerostin-positive cells in fibrous tissue than in bone, showing a phenotype like mast cells with strong dot-cytoplasmic positivity. The analysis of sclerostin-positive cell lesions (scored as 2 and 3) showed also tryptase positivity in 80.9% of 21 biopsies. β-catenin was diffusely expressed on the fibrous component, mostly with cytosol staining. Non-lesional bone showed sclerostin expression in medullary spaces and a few osteocytes.

Sclerostin-positive cells are mostly found in the fibrous tissue of FOL, and the tryptase mast cell marker was present in most of the lesions that were positive for sclerostin.