The quantification and significance of mast cells in lesions of Behçet's disease.

SUMMARY Mast cells in the upper dermis and mucosal subepithelial layer were counted in thirty consecutive light microscopy oil-immersion fields of the following: thirty-four skin and oral specimens from lesions in patients with active Behcet's disease, eight specimens of apparently uninvolved skin of the same patients, and 102 lesions of a variety of other skin diseases. The results revealed a significant increase in the number of mast cells in Behcet's lesions. Furthermore, the histamine content of five reactive lesions showed a two-fold increase compared with that in apparently uninvolved skin of patients with active Behcet's disease. It is suggested that mechanisms similar to cutaneous basophil hypersensitivity may be involved in the production of Behcet's lesions.