Hemophagocytic syndromes vs. hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is an inhibitory immune regulation disorder that has been well-characterized in pediatric patients, where it shows a clear genetic etiology. However, in adult patients, certain infections, rheumatological disorders and, above all, some hematological malignancies, have a greater pathogenic weight in their development, although the extent of the impact of facilitating genetic factors remains unknown to date. For this reason, as it happens in other hyperinflammatory conditions, this predisposition should be investigated, because, in adult patients, HLH is not well known, rarely suspected, and probably underdiagnosed. The rapid establishment of clinical suspicion and diagnostic maneuvers will allow early initiation of treatment, which should generally be started without confirmatory immunological or genetic testing. Treatment needs to be administered on an individual basis and conducted in expert centers. In general, in pediatric patients, as well as in hematological malignancy-related HLH, treatment consists of immunosuppression with etoposide, while in cases associated with infections or macrophage activation syndromes, treatment targeted directly at the etiological cause is often enough, as long as patients remain clinically stable. In the case of disease worsening, whatever the cause, immunosuppression will be needed. The term “hemophagocytic syndrome” should, therefore, be abandoned and replaced by HLH.