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A 56-year-old woman with a history of systemic lupus erythematosus presented with enlarged right axillary lymph nodes, the largest measuring 2.3 cm. The patient underwent an excisional biopsy. The lymph nodes showed follicular and paracortical hyperplasia with prominent clusters of plasmacytoid dendritic cells (pDCs; panels A-B; original magnification ×40 [A] and ×400 [B], hematoxylin and eosin stain). In addition, there were more classical, but less prominent, features of lupus lymphadenitis: focal areas of necrosis in the paracortex with nuclear debris and hematoxylin bodies (panel C; original magnification ×400, hematoxylin and eosin stain). The pDCs stained positive for CD123 (panel D; original magnification ×100). They were also positive for CD68 and granzyme B, and negative for B-cell lymphoma 2 (BCL2), CD56 (panels E-H; original magnification ×100), and terminal deoxyribonucleotidyl transferase (TdT). In contrast to benign pDCs, their neoplastic counterparts are positive for BCL2, CD56, and TdT. Plasma cells, highlighted by CD138, were increased in the germinal centers and in the paracortex. Immunohistochemical studies with CD20 and CD5 showed well-preserved B- and T-cell compartments, respectively.Recent research has highlighted the role of pDCs as a source of type 1 interferon in the pathogenesis of lupus. In summary, although not specific (also seen in Castleman disease and Kikuchi lymphadenitis), clusters of pDCs are a useful clue to support the diagnosis of lupus lymphadenitis.