J Gen Intern Med. 2020 Aug 19. doi: 10.1007/s11606-020-06141-1. Online ahead of print.
A fever of unknown origin is often pursued diagnostically under the framework of infectious, rheumatologic, and neoplastic causes. When encephalopathy ensues, the differential diagnosis narrows, but can remain elusive, particularly when dealing with rare diseases. We present the case of a patient with fever of unknown origin and intermittent encephalopathy that spanned multiple hospital admissions and ultimately yielded a diagnosis of intravascular large B cell lymphoma complicated by
hemophagocytic lymphohistiocytosis. We review the varying presentations of this disease, when to consider this as a diagnosis, and how to most accurately make the diagnosis.