Myeloperoxidase expression by histiocytes in Kikuchi's and Kikuchi-like lymphadenopathy.
Pileri SA, Facchetti F, Ascani S, Sabattini E, Poggi S, Piccioli M, Rondelli D, Vergoni F, Zinzani PL, Piccaluga PP, Falini B, Isaacson PG.
Pathology and Clinical Units, Institute of Hematology and Clinical Oncology L. & A. Seragnoli, Bologna University, Bologna, Italy. pileri@almadns.unibo.it

Forty-five examples of Kikuchi's lymphadenitis (KL), 5 Kikuchi-like lupus erythematosus lymphadenopathies, 25 nonnecrotizing lymphadenitidies (5 toxoplasmic, 5 sarcoid-like, 6 dermatopathic, 4 suppurative, 3 tubercular, 2 with sinus histiocytosis), 4 examples of hyaline-vascular Castleman disease (CD), 2 plasmacytoid monocyte tumors (PM-Ts), and 61 accessory cell neoplasms were studied by a panel of antibodies, including the PG-M1 (against a macrophage-restricted CD68 epitope) and a polyclonal anti-myeloperoxidase (MPO). In KL and Kikuchi-like lupus erythematosus lymphadenopathies, 25 to 75% of CD68(+) histiocytes co-expressed MPO. This did not occur in nonnecrotizing lymphadenitidies and accessory cell neoplasms. MPO(+)/CD68(+) elements corresponded to nonphagocytosing mononuclear cells and some crescentic macrophages and phagocytosing histiocytes. Typical PMs were MPO(-)/CD68(+) in all cases, including CD and PM-T. Our observations suggest that in KL and KL-like lymphadenopathies: 1) MPO(+)/CD68(+) blood monocytes might be attracted into tissues because of the lack or paucity of granulocytes and the need of MPO for oxidative processes; 2) PMs are more likely to be involved in the cytotoxic immune reaction than in phagocytic phenomena; 3) the peculiar phenotype of the histiocytic component can be usefully used for the differentiation from malignant lymphoma and PM-T.

PMID: 11549584 [PubMed - indexed for MEDLINE]