Hemophagocytic lymphohistiocytosis (HLH) is a rare systemic inflammatory disorder that is rapidly progressive and carries a poor prognosis. We present a case of HLH caused by undiagnosed B cell lymphoma, presenting initially with splenic infarction. Both HLH and splenic infarction are secondary conditions with a wide range of underlying etiologies. When either condition is identified, a prompt search for the underlying trigger is needed to prevent devastating consequences. We demonstrate the difficulties and barriers that can delay the diagnosis of HLH, and emphasize the importance of early treatment in improving survival rates.