Spatial distribution of mast cells in chronic venous leg ulcers.

Chronic venous leg ulcers (CVUs) show chronic inflammation but different pathological changes occur in different parts of the ulcer. There is a lack of re-epithelialisation and defective matrix deposition in the ulcer base but epidermal hyperproliferation and increased matrix deposition in the surrounding skin. The role of mast cells in wound healing, inflammation, fibrosis and epidermal hyperproliferation has been extensively studied but less is known about their role in CVUs. In the present study, we investigated the distribution of mast cells in CVUs with specific consideration of the differences between the ulcer base and the skin surrounding the ulcer. Both histochemical and immunohistological methods were used to detect the mast cell marker tryptase in frozen sections of CVU biopsies. Mast cells were counted in the dermis of normal skin, in the ulcer base and in the skin surrounding the ulcer. Double immunofluorescence staining was used to study the location of mast cells in relation to blood vessels. In normal skin few mast cells were seen in the dermis but none in the epidermis. However in CVUs there was a significant increase in intact and degranulated mast cells in the surrounding skin and ulcer edge (184 per field, p