Kikuchi-Fujimoto Disease

Lessons From the Friday Unknowns

The biopsy specimen shows lymph node with somewhat preserved architecture.

The paracortical regions are expanded by numerous histiocytes, plasmacytoid dendritic cells and small lymphocytes with many apoptotic cells. No granulocytes are observed.

Wedge-shaped areas of histiocytes, some with C-shaped morphology

The uninvolved lymph node shows preserved B-cell and T-cell regions.

CD3 and CD20 stains highlighting preserved follilces and inter-follicular T-cell areas

The expanded paracortical regions are composed of many CD68+ histiocytes and many T-cells positive for CD3, CD5, CD7 and CD8. The antibody specific for CD4 highlights T-cells (less than CD8+ cells) and many histiocytes. The antibody specific for granyzme B shows many cytotoxic lymphocytes in…