Site-specific immunophenotyping of keloid disease demonstrates immune upregulation and the presence of lymphoid aggregates

Summary Background Keloid disease (KD) is a common fibroproliferative disorder of unknown aetiology. T cells and macrophages are increased in KD and are thought to contribute to its pathogenesis. However, while a link between inflammation and fibrotic disorders is well known for other disorders, it remains undetermined in KD. Objectives Systematically to immunophenotype the inflammatory infiltrate of KD in situ in a site‐specific manner, and to compare this with normal skin and scar tissue. Methods Sixty‐eight keloid cases were screened for the presence of all three (intralesional, perilesional and extralesional) keloid‐associated specific tissue sites. Subsequently, a complete set of 25 keloid biopsies (from different patients) was compared with normal skin (n = 11) and normal scar (n = 11) samples and subjected to systematic, site‐specific quantitative immunohistomorphometry and histochemistry, using a range of immunological markers of B cells, T cells, macrophages, mast cells (MCs) and Langerhans cells. Results T cells, B cells, degranulated and mature MCs (coexpressing OX40 ligand) and alternative macrophages (M2) were all significantly increased in intralesional and perilesional KD sites compared with normal skin and scar tissue (P