Suppurative lesions without prominent epithelioid cell response in abscess-forming granulomatous lymphadenitis

To clarify the clinicopathological significance of the suppurative lesions without an epithelioid granulomatous response (SLs without Ep) in lymph nodes and their relationship to abscess-forming granulomatous lymphadenitis (AGL) and cat scratch disease (CSD), 10 cases were assessed clinicopathologically and immunohistologically. SLs without Ep were located in the subcapsular sinus, paracortical area and medullary cords, but not in the germinal centers. The microabscesses were surrounded by collections of monocytoid B-lymphocytes (MBLs), histiocytes without epithelioid features, neutrophils, small lymphocytes and small numbers of plasma cells. The majority of the MBLs seen in the SLs without Ep were of the large cell type. The histological triad of toxoplasmic lymphadenitis, i.e., reactive follicular hyperplasia, small clusters of epithelioid cells and aggregates of MBLs, were also seen in all cases. Some of the clinical and pathological findings in our 10 cases were characteristic of CSD, i.e., (1) cat exposure before the lymphadenopathy was in four of the 10 cases, (2) occurrence in autumn and winter months in all cases, (3) typical suppurative granulomas surrounded by palisaded epithelioid cells were in four of the 10 cases, and (4) Warthin-Starry silver stain-positive bacteria were detected in seven of the 10 cases. The results of our study suggest that SLs without Ep are an early stage of CSD.