Pseudofungi in a lymph node: A case report with energy dispersive X-ray elemental analysis

A case of pseudofungi in axillary lymph nodes is presented. They resembled septate hyphae and were stained with a periodic acid-Schiff stain. Gomori methenamine silver stain failed to stain them. Because of morphologic similarity to true septate fungi and positive staining with periodic acid-Schiff stain, these structures can be misinterpreted as septate hyphae forming true fungal organisms. Further studies, some of which included energy-dispersive x-ray elemental analysis and special stains, revealed that they were composed of iron, phosphorus, and calcium. The relationship of these pseudofungi to previously published cases and clues that enable one to make a correct diagnosis are described.