Hemophagocytic Lymphohistiocytosis Secondary to Bone Marrow Only B-Cell Lymphoma: A Very Rare Entity With an Even Rarer Presentation

Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory syndrome. It is categorized as familial or acquired, most commonly caused by infections, malignancies, rheumatologic and immunodeficiency disorders. Irrespective of the etiology, the age at the onset is the strongest prognostic factor, hence it is extremely important to have a high suspicion for HLH, diagnose it promptly and initiate treatment without any delay. We encountered a 70-year-old female patient who initially presented with left-sided facial weakness and pancytopenia, secondary to diffuse stage IV B diffuse large B-cell lymphoma with isolated bone marrow involvement with secondary HLH.