A patient has had a draining fistula for over two years. Which type of inflammatory cells predominate in the lesion?

A fistula persisting for two years is consistent with a chronic infection. In chronic inflammation, the predominant cells are lymphocytes and plasma cells (which produce antibodies as part of the adaptive immune response). Macrophages are also present. Neutrophils are the hallmark of acute inflammation and are recruited early in infection, but they do not persist for years. In a chronic periapical granuloma or cyst, histopathology typically reveals a dense infiltrate of lymphocytes, plasma cells, and macrophages. The presence of plasma cells also reflects ongoing B-cell-mediated antibody production against bacterial antigens.