Infectious diseases evaluation of the child with suspected hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive and maladaptive inflammation. Classic clinical and laboratory features associated with the diagnosis of HLH, including fever, cytopenias, hyperferritinemia and splenomegaly, are not specific to HLH and can be caused by infections. Fulfillment of these clinical and laboratory criteria alone are not sufficient to diagnose HLH or initiate HLH-directed therapies. In this manuscript, we review the pathogenesis of HLH and HLH-like syndromes associated with infection. We offer a paradigm for evaluating patients with suspected HLH to identify key exposures, diagnose and treat infection before initiation of immunosuppression.