Estimation of apoptosis and cell proliferation in histiocytic necrotizing lymphadenitis using immunohistochemical double staining

The aim of the present study was to estimate the relationship between apoptosis and cell proliferation in histiocytic necrotizing lymphadenitis (HNL). Fifteen patients with HNL were retrospectively analyzed. The patients were divided into three groups according to the proportion of the necrotic area as follows: necrosis (+), necrotic area <25%; necrosis (++), necrotic area 25–50%; and necrosis (+++), necrotic area >50%. Immunohistochemical double staining was performed for CD3 plus caspase-3 and for Ki-67 plus caspase-3 and positive cells were counted in two areas: one without and one with obvious apoptotic features. Most caspase-3-positive cells were also stained for CD3 (area exhibiting obvious apoptotic features: average, 92.3%). Furthermore, various proportions of both Ki-67- and caspase-3-positive cells were detected in all the groups (range, 5–70%). In the area with obvious apoptotic changes, the average percentage of both Ki-67- and caspase-3-positive cells (38.6%) was higher than that in the area without obvious apoptotic features (16.3%). A proportion of cells in HNL undergo proliferation and apoptosis simultaneously, such as neoplastic cells, thereby exhibiting rapid cell cycles.