Rosai-Dorfman Disease Mimicking Metastasis to the Spleen From Breast Cancer

Rosai-Dorfman disease is a non-Langerhans cell histiocytosis with ubiquitous distribution. Although more common in lymph nodes, it has been described in many organ systems. The current case depicts a 54-year-old woman with a history of estrogen receptor-positive breast carcinoma who showed different image features of metastatic lymph nodes and splenic Rosai-Dorfman disease on FDG and FES PET/CT scans.