A 14-year-old patient with history of IgA vasculitis (Henoch-Schonlein purpura) was admitted for fevers, cervical lymphadenopathy, rash and gross hematuria. Laboratory results showed systemic inflammation with elevated ferritin, C-reactive protein, hypoalbuminemia, and acute kidney injury (AKI). Infectious disease work-up was negative. A lymph node biopsy was performed and demonstrated follicular and paracortical hyperplasia on H&E (Fig. 1A, × 40). The nodes showed areas with pink appearance (Fig. 1B, × 100) corresponding to involuted germinal center cells replaced by histiocytes with oval, crescent-shaped, or folded nuclei (short arrows). There was focal phagocytic activity, single-cell necrosis, and karyorrhectic debris/necrosis (long arrows) (Fig. 1C, × 500). In other areas, collection of macrophages was noted (Fig. 1D, × 200) although neutrophils and eosinophils were rare/absent. Immunostaining for CD20 showed abundant interfollicular B-cells but not in the germinal centers (Fig. 1E, × 100). CD3 stained interspersed T-cells (Fig. 1F, × 100) predominantly positive for CD8 (Fig. 1G, × 100). CD23 highlighted distorted/peripheralized follicular dendritic cell meshwork associated with germinal centers (Fig. 1H, × 40) containing CD68 + histiocytes (Fig. 1I, × 100), also positive for myeloperoxidase (Fig. 1J, × 100). CD123 stained plasmacytoid dendritic cells around the follicular structures (Fig. 1K, × 100). CD30 was positive in scattered immunoblasts and PD1 in few follicular helper T-cells (not shown). CD138 revealed plasmacytosis (Fig. 1L, × 40) polytypic for Kappa and Lambda light chains (not shown). Overall, adenopathy in IgA vasculitis shows features of Kikuchi-Fujimoto lymphadenitis (proliferative and necrotic phases) and is peculiar for the abundance of germinal center histiocytes (follicular granulomas), with rare cases reported [1]. The etiology likely includes an autoinflammatory or autoimmune process. The patient was treated with near resolution of rash, lymphadenopathy, improved AKI, and down trending inflammatory markers.

Fig. 1
figure 1

Lymph node biopsy in a case of IgA vasculitis

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