Rosai-Dorfman Disease Presenting as Massive Mediastinal Lymphadenopathy in an Elderly Man.

We present a patient case of a 73-year-old man with new-onset substernal chest pain and B symptoms, found on computed tomography imaging to have massive mediastinal lymphadenopathy of more than 6 cm. Positron emission tomography imaging revealed fluorodeoxyglucose-avid nodes further extending to the axillary, abdominal, and inguinal regions. After a broad patient work-up for infectious, malignant, and rheumatic causes, he was ultimately diagnosed with Rosai-Dorfman disease, a rare histiocytic neoplasm, by excisional lymph node biopsy.