Lymphoid malignancy-associated hemophagocytic lymphohistiocytosis: Search for the hidden source.

Secondary hemophagocytic lymphohistiocytosis (HLH) is an uncommon, but life-threatening syndrome of highly stimulated and ineffective immune dysregulation. It is not a disease entity by itself and the current diagnosis of secondary (acquired) HLH is based on constellation of nonspecific clinical and laboratory parameters indicative of overactive immune response. The presenting symptoms are often nonspecific and could potentially be missed, leading to a fatal outcome. Patients with malignancy-associated HLH have a relatively unfavorable overall survival compared with non-malignancy-associated HLH. In this retrospective study, nine adult patients with secondary HLH were identified. Of these four cases were associated with a malignancy and despite a high degree of suspicion, the underlying lymphoid malignancy was not initially evident. Three out of four patients with lymphoid malignancy-associated HLH died over a very short course of time following the diagnosis. The outcome was significantly different for the control group of patients with other underlying cause(s) for HLH. These cases emphasize the importance of a thorough search for a hidden malignant source in patients with secondary HLH for prompt diagnosis and institution of malignancy specific treatment.